Most Tech Interview Prep is GARBAGE. (From a Principal Engineer at Amazon)

Way too many software engineers burn their time on technical interview prep that’s just coding drills. Sure, that might help if you’re fresh out of school, but once you’re aiming for senior or principal roles at big tech companies, that’s just not enough.

Let’s be real: companies interview because they have to make hiring calls quickly, often with very little to go on. A bad hire? That can easily blow through hundreds of thousands of dollars and drag on for over a year. Senior roles aren’t just about solving algorithm puzzles—they’re about designing big systems and leading people.

Key Takeaways

• Technical interviews really come in three flavors: coding, system design, and leadership
• Most folks prepping for interviews obsess over coding and totally skip the system design and leadership stuff
• System design questions may sound theoretical, but they’re really just checking if you’ve actually built similar things before

Understanding the Purpose of Technical Interviews

The Stakes and Costs of Hiring

Hiring mistakes are expensive—sometimes painfully so. The total cost of a bad hire, once you add it all up, can hit $500,000 to $1 million. Ouch.

It usually takes about six months before a company realizes someone isn’t a good fit. Then it’s another six months, maybe even a year, to actually move them out. The whole time, you’re still paying:

• Big salaries
• Benefits
• Rent for their desk
• Equipment
• Recruiting fees

And that’s not even counting the ripple effects:

• Software quality tanks
• Technical debt piles up
• Team morale drops
• For smaller companies, it can even threaten survival

On the flip side, a great hire? They write solid code, spot problems before they blow up, improve what’s already there, and help set the bar for quality. They also tend to attract other strong engineers and help the whole team level up.

Time Constraints in Candidate Evaluation

There’s just not much time to figure people out in interviews. Most companies get maybe six hours—tops—to decide if someone’s the right fit for a senior role.

That’s wild, considering senior hires at big companies often take half a year before they really start making an impact. But interviewers have to make that call after just a handful of hours.

Internships are great for entry-level folks since they’re basically two-month-long interviews. But for senior and principal positions? Yeah, not an option.

So, companies end up looking for shortcuts—ways to spot the right people as quickly as possible.

Proxies in Interview Assessment

Because there’s no time for deep dives, companies rely on proxies—quick tests that hint at real ability. These need to be tough to game and actually say something about how you’ll do on the job.

Modern interviews lean on two big ideas:

1. Using proxies instead of direct assessment – Since you can’t really test someone’s full skills in a few hours, you use condensed challenges
2. Making sure those proxies are hard to fake – You want questions where only people who really know their stuff can shine

Data structures and algorithms are classic proxies for coding chops. Sure, you might not use them every day, but if you know them, you probably know how to code. If you don’t, good luck bluffing your way through.

The three-level interview structure usually looks like this:

For senior and principal positions, companies want people who’ve worked on big, multi-year projects and can lead teams. It’s not just about writing code—it’s about making the whole thing work.

System design questions may look like they’re about hypotheticals, but really, they’re testing if you’ve got hands-on experience. When you get grilled about scaling, uptime, or performance, it’s pretty easy to tell who’s actually built something similar and who’s just read about it.

Why Most Technical Interview Preparation Approaches Don't Work

Issues with Programming-Heavy Study Materials

Most prep books and websites? All about coding challenges. That’s fine if you’re just starting out, but if you’ve been in the game a while, it’s missing the mark.

Coding questions are just the first hurdle. They’re table stakes, not the whole game—especially for senior roles. Companies expect a lot more than just code from you at that level.

Honestly, spending months grinding through algorithms is a waste for senior candidates. That’s time you could be spending on things that actually matter for the roles you want.

Problems with Junior-Level Preparation Methods

Prep guides and YouTube tutorials? Most are aimed at juniors. They hammer on data structures and algorithms because, well, that’s what entry-level interviews focus on.

But senior engineers need to be ready for:

• System design scenarios
• Leadership questions
• Architecture tradeoffs
• Team management situations

Most entry-level prep doesn’t even touch this stuff. That leaves experienced engineers walking into interviews totally unprepared for the questions that really matter.

So, you end up with folks who ace the coding round but get blindsided when it comes to design or leadership. That’s a recipe for disappointment.

Dangers of Excessive Algorithm Practice and Course Dependency

It’s easy to get sucked into the LeetCode grind. You solve hundreds of puzzles and start thinking you’re ready for a senior gig at Google or Amazon.

But here’s the kicker:

• Algorithm questions are just filters
• They weed out people who can’t code
• They don’t say much about system design
• They don’t test your leadership chops

Paid interview courses often make things worse. They promise results if you just do more coding drills. People drop hundreds of dollars only to get more of the same.

This approach backfires. Not only does it eat up time that could be spent on more relevant prep, but it also gives you confidence in the wrong areas.

Each interview level needs its own kind of prep:

Most resources barely touch Levels 2 and 3. So, senior candidates walk in ready to code, but when the real questions start, they’re caught flat-footed.

And honestly, the lost time is brutal. Every extra hour on code puzzles is an hour you’re not preparing design stories or leadership examples—the stuff that really moves the needle for senior interviews.

Core Skills Required for Advanced Engineering Positions

Programming Skills as a Foundation

Let’s not kid ourselves—if you can’t code, you’re not getting the job. You need to write code daily, spot better solutions, and know when a bad algorithm is going to tank your system.

This is the first gate in any technical interview. If your coding isn’t solid, you won’t even get to the interesting questions. That’s why companies use algorithm and data structure questions—they’re hard to fake.

Some key programming abilities:

• Algorithm efficiency: Why does this code run faster than that?
• Data structure savvy: Picking the right tool for the job
• Problem-solving under pressure: Can you code when the clock’s ticking?

Most prep stops here. But if you spend all your time here and you’re shooting for a senior role, you’re missing out on what actually matters next.

Advanced Skills: Team Leadership and Architecture Design

Senior engineers need to do a lot more than just code. They’re designing systems that take teams of people months, maybe years, to build. They’re the ones making the big calls and leading the technical direction.

System architecture is the next level. Companies want people who can see the big picture, fix what’s broken, and build new things that last.

These skills come from real-world experience, not cramming. You need to know:

• Where big systems tend to break down
• How to keep things running for millions of users
• Which shortcuts will bite you later
• How to build stuff that doesn’t fall over at 2am

Leadership is the final piece. Senior folks help others grow, make tough technical choices, and often bring in more great engineers. It’s a virtuous cycle.

Good leaders don’t just code—they build teams that get better over time.

What Top Technology Companies Actually Want

Big tech companies want people who can handle long, complex projects with big teams. They’re looking for engineers who get both the tech and the business side of things.

Since you can’t test all that in six hours, interviews use proxies. The real proof comes months later, but you’ve got to show hints of it right away.

System design questions sound hypothetical, but they’re really about your past. The strongest answers come from people who’ve been there and done that.

Expect questions about:

• Scaling to millions of users
• Keeping things up and running
• Making software fast everywhere
• Handling mountains of data

Specific stories from your own work always land better than vague theory. If you can’t point to real projects, interviewers can usually tell.

There’s a lot riding on these decisions—bad hires are expensive and slow things down for everyone. Good ones make the whole team better.

Three Stages of Technical Interviews

Interviews at top tech companies are basically a three-level gauntlet. You’ve got to clear each one to get the offer.

Each stage is looking for something different. It’s all about finding quick, reliable ways to spot the right people.

Stage One: Programming Skills

Coding is the foundation. You’ll get hit with programming questions to prove you can actually build things.

Why do these matter?

• They show you know the basics
• Bad code stands out fast
• It’s tough to fake live coding

Most people prepping for interviews stop here, which is a mistake for senior roles.

Expect questions about:

• Data structures and algorithms
• Making code run faster
• Solving problems when the clock’s ticking

This round is mostly a filter. If you can’t code, you’re out.

Stage Two: Architecture Planning

System design interviews check if you can actually build big, complex systems. These aren’t weekend projects—they take teams months or years.

Companies want people who can jump in and start making an impact, not just write code in isolation. Architecture questions are the best way to check for that.

Topics you’ll see include:

• How to scale things up
• Database design choices
• Performance tuning
• Keeping things reliable

Design questions are supposed to sound like hypotheticals, but really, they’re looking for your real experience. If you’ve built something similar, it shows. If not, it’s tough to fake.

Watch for follow-ups like:

• How would you scale to millions?
• What if a server crashes?
• How do you keep things snappy?

Best answers come from your actual work—not just textbook knowledge.

Stage Three: Leadership and Team Contribution

Senior engineering roles are about a lot more than just writing code or designing systems. Companies want folks who can actually guide teams and raise the bar for everyone around them.

Leadership indicators:

• Making technical calls that affect multiple teams
• Mentoring engineers (even when it’s not “your job”)
• Helping resolve team conflicts—because, yeah, they happen
• Pushing projects over the finish line (not just starting them)

Honestly, the best way to dig into this stuff is with behavioral questions—asking people to walk through real situations they’ve faced, not just hypotheticals.

Example behavioral questions:

• Tell me about a time you disagreed with your team
• Describe a project where you had to influence people outside your team
• Share an example of how you improved code quality across multiple teams

It’s a lot harder to fake your way through these than through “what would you do if…” style questions. Anyone can talk a good game about leadership, but only folks with the scars have the stories.

This stuff really ramps up at the principal or staff level. At that point, you’re spending more energy on technical leadership than on cranking out code yourself.

Understanding Technical Interview Success

Breaking Down Complex Software Architecture

Big systems are, well, big. They’re made up of a bunch of moving parts, usually built and kept alive by teams of people over months or years. It’s a whole different beast from solo projects.

When you get system design questions, they’re not just checking if you can sketch out an architecture—they’re trying to figure out if you can actually help with their real, messy projects. You don’t learn system design the same way you grind through coding puzzles.

It’s a bit like building a bridge. You need some real-world miles to know where things break down, where you can cut corners, and where you absolutely can’t.

Here’s what matters most in big systems:

• Lots of components that have to play nicely together
• Coordination—not just between code, but between people
• Maintenance—stuff needs to last and evolve
• Scaling—sometimes to millions of users (no pressure)

Types of Interview Questions You Will Face

System design questions aren’t like coding ones. They might sound like “what would you do?” but, honestly, they’re more like “what did you actually do?”

Situational questions are about made-up scenarios. Most coding interviews are like this: “Here’s a problem, how would you solve it?”

Behavioral questions dig into your real-life experiences—they want to know what you’ve actually done before.

So, system design questions? They’re tricky. They sound situational (“How would you design Facebook’s news feed?”), but what the interviewer really wants is to hear about something you’ve built that’s even a little bit like it.

The follow-ups are where they get you:

• How would you handle millions of users?
• How would you keep the system running?
• How would you make it fast with lots of data?

If you haven’t built big systems, these are tough to answer convincingly.

Connecting Classroom Knowledge to Industry Work

There are three main “levels” in software interviews. You’ll need to get through all of them to land an offer.

Level 1: Coding Skills This is about writing code and knowing why some solutions are slow. Most people spend all their prep time here.

Level 2: System Design This is about working on big, messy projects with lots of people. Companies care about whether you can improve what they already have.

Level 3: Leadership Can you guide other engineers and make solid decisions?

Most folks spend way too long grinding LeetCode. If you’re aiming for a senior role, that’s not the best use of your time.

Here’s the thing: you can study coding problems in a book, but you can’t fake experience building real systems. You need to have actually built stuff that real users depend on.

Interviewers know this. They’ll ask tough follow-ups to see if you’re the real deal. The more senior the role, the more they’ll dig.

At the end of the day, the only way to really get good at this is to build real, large-scale systems. Studying helps, but it’s not a substitute for experience.

Understanding Question Types in Technical Interviews

Telling Apart Behavioral and Situational Problems

There are basically two kinds of questions you’ll see in tech interviews, and they’re meant to test different things.

Situational questions ask what you’d do in a made-up scenario. You’ll hear things like “What would you do if…” or “How would you handle…” Coding questions? They’re all situational.

For example, if someone asks about balancing a binary tree, they’re really saying: “If you had to do this, how would you approach it?” It’s about thinking on your feet.

Behavioral questions dig into actual experiences you’ve had. They usually start with “Tell me about a time when…” and they want the real story.

Here’s the quick cheat sheet:

• Situational = What would you do?
• Behavioral = What did you do?

Recognizing Behavioral Elements in System Design Questions

System design questions love to disguise themselves as situational, but they’re really fishing for your past experience. “How would you design Facebook’s news feed?”—yeah, it sounds hypothetical, but that’s not what they’re after.

What they want is to know if you’ve ever tackled something even remotely similar.

You might sketch something out on a whiteboard, but then the real grilling starts:

• How’d you scale this to millions of users?
• How’d you keep it running 24/7?
• How’d you make it fast with a ton of data?

It’s way easier to answer these if you’ve done it before. Companies really want people who’ve solved these problems in the wild.

Showing Leadership Through Past Experience

Leadership questions? They follow the same pattern as system design. They’re just way more useful when they’re behavioral, not situational.

A situational leadership question might be: “What would you do if you disagreed with your team?” It’s easy to give a textbook answer.

The behavioral version is tougher: “Tell me about a time you disagreed with your team.” Now you need a real story, with real details:

• What was the disagreement?
• How did you handle it?
• What happened in the end?
• What did you take away from the experience?

Why behavioral questions work better for leadership:

• They’re much harder to fake
• They show real problem-solving skills
• They reveal your actual behavior when things get rough
• They show if you’ve learned and grown from tough situations

For senior roles, companies lean heavily on these behavioral leadership questions. They need proof you’ve actually led teams and made the hard calls.

The strongest answers have numbers, timeframes, and outcomes. That’s how you show you know what impact your decisions really had.

Smart Study Methods for Senior Tech Interviews

Targeted Learning for Better Results

Most folks prepping for senior interviews waste way too much time on coding drills. It’s fine for new grads, but if you’re experienced, it’s not where you should focus.

The Three Interview Levels:

Companies are looking for engineers who’ve actually built big systems with big teams—over years, not weeks. They want real proof you’ve done it before.

Key Study Areas:

• Large-scale system architecture
• How to scale databases
• Load balancing tricks
• Caching strategies
• Microservices patterns

If you’re short on time, spend it on levels 2 and 3. Coding skills just get you in the door.

Using Your Work History Effectively

Your past experience is your best weapon in senior interviews. Companies want people who’ve solved real problems, not just hypothetical ones.

System design questions might look like puzzles, but they’re really about your background. If they ask you to design a social media feed, they want to know if you’ve built something even a little bit like it.

Experience Areas to Highlight:

• Systems that served millions of users
• Making databases run faster
• Coordinating teams on tough projects
• Making the right technical calls
• Solving problems when things went sideways

The follow-ups are where it gets real. Questions about scaling to billions or keeping things online 24/7 are way easier if you’ve actually done it.

Jot down 5-7 stories from your career—cover the problem, what you did, what happened, and what you learned. You’ll thank yourself in the interview.

Showcasing Your Technical Projects and Team Leadership

Senior interviews really come down to proving you’ve led before, and not just in theory. Interviewers want to hear about what you’ve actually done, not what you think you’d do.

Strong Project Stories Should Include:

• The business problem you tackled
• Technical hurdles you ran into
• How you shaped or nudged the team
• Clear, measurable results
• Something you genuinely learned

Weak example: "I would handle team disagreement by listening to all sides."

Strong example: "When our team couldn’t agree on a database, I set up technical deep-dives, put together comparison docs, and eventually helped us pick an option that boosted performance by 40%."

Leadership Areas to Prepare:

• Mentoring newer engineers
• Working across teams (it’s trickier than it sounds)
• Making tough calls on technical debt
• Planning projects and actually shipping them
• Responding when systems break (because they will)

Try to choose stories that show you’ve grown and taken on more responsibility over time. It helps if you can highlight moments where your technical chops made a real difference.

It’s worth practicing these stories until you can tell them in just a couple of minutes—think quick setup, what you did, and what happened. Interviewers don’t have all day, so make your role and the challenges obvious fast.