10 Lessons I Learned from a Principal Engineer That Made Me a Better Developer

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10 Lessons I Learned from a Principal Engineer That Made Me a Better Developer

I still remember the first one-on-one I had with our principal engineer. I had just joined the team, eager to prove myself. I expected a technical grilling, but instead, we talked about design principles, business impact, and something he called “engineering maturity.” That conversation shifted my mindset completely.

Over the next year, I shadowed him on tough projects, joined architecture discussions way above my pay grade, and watched how he operated under pressure. What I learned from him transformed how I code, communicate, and contribute.

Here are 10 lessons that made the biggest impact:

1. Write Code for the Engineer Who Replaces You

“Your code should tell a story,” he said. “One that the next person can follow without guessing the plot.”

That hit me. I stopped writing clever one-liners and started leaving meaningful comments. I wrote clearer function names and modular code, not just for myself – but for the poor soul debugging it six months later.

2. Slow is Smooth. Smooth is Fast.

I used to rush deployments, patching things in the name of speed. He showed me how that rush often leads to mistakes that cost more time later.

Instead, he moved calmly – even in production incidents. Double-checked assumptions. Asked better questions. Funny thing? His approach actually got things done faster, with fewer rollbacks.

3. Understand the Business, Not Just the Code

“You can build the perfect feature,” he said, “and still miss the point if you don’t know why it matters.”

He taught me to ask:

• Who are we building this for?

• What problem does it solve?

• How does it drive business value?

This mindset helped me prioritize better, push back when necessary, and even propose smarter solutions.

4. Read the Codebase Like a History Book

During a code review, I asked, “Why is this done this way?”

He replied, “Have you checked the git history?”

Turns out, the odd pattern I was questioning was the result of three product pivots and a customer escalation.

Lesson? Don’t assume the code is dumb – assume there’s a story behind it.

5. Never Say ‘Just’

“Let’s just add a quick API.”

“Can’t we just change the schema?”

He banned the word “just” in architecture meetings. It oversimplifies problems, hides complexity, and leads to poor planning.

Now, whenever someone says “just,” I pause and ask: Is it really that simple?

6. Choose the Right Abstraction, Not the Most Abstract

He once refactored my beautiful, reusable, generic class into three simple, repetitive functions.

“Premature abstraction is worse than duplication,” he said.

I learned that good architecture isn’t about DRY at all costs – it’s about readability, maintainability, and fit for purpose.

7. Learn to Communicate Up, Down, and Across

Watching him present to leadership was a masterclass. No jargon. Clear trade-offs. Business impact front and center.

He also tailored messages: technical depth for engineers, high-level goals for PMs, reassurance for stakeholders.

Communication isn’t soft skill fluff – it’s a core part of being a senior developer.

8. Logs Are Your Love Letters to Future You

“Write logs like you’re writing to yourself at 2 a.m., half-asleep, trying to debug a crash in production.”

Since then, I’ve become obsessed with thoughtful logging:

• What was the system trying to do?

• What inputs did it receive?

• What failed – and why?

Good logs are like time machines. They save you more than tests sometimes.

9. Know When to Leave Things Broken (Temporarily)

Not every bug needs an immediate fix. Not every tech debt item deserves a sprint.

He taught me how to triage effectively – understand risk, assess impact, and make strategic decisions.

“Engineering isn’t about perfection,” he said. “It’s about judgment.”

10. Seniority Is Measured by How Much You Amplify Others

The most surprising lesson? His impact wasn’t just in his code – it was in how he made everyone else better.

• He mentored without ego.

• Gave credit generously.

• Stepped back so others could step up.

He told me: “You become a better developer not just when your code improves – but when your team does.”

Final Thoughts

I didn’t become a principal engineer after working with him – but I started thinking like one. That shift has influenced every project I’ve touched since.

These lessons weren’t always comfortable, and some I had to learn the hard way. But each one helped me grow – not just as a developer, but as a teammate, leader, and thinker.

If you’re lucky enough to work with someone like that, pay attention. Watch how they move. Listen more than you speak. And carry their lessons forward.

Because good engineers build features.

Great ones build people.

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