**Myth:** You need to understand every line of code in your codebase to be a "real" developer.

Myth: You need to understand every line of code in your codebase to be a "real" developer. Reality: Nobody understands the whole thing. Not even the people who wrote it. We're all just really good at pretending. Last Tuesday, I watched a senior developer spend three hours explaining a system he built six months ago. By hour two, he was taking notes. His own notes. On his own code. At one point he said "oh, that's clever" and then immediately looked terrified because he didn't remember being that clever. The codebase I'm working on has 847,000 lines. I've read maybe 12,000 of them. The rest is held together by what I call "architectural faith" and what my coworker calls "please don't break, please don't break, please don't break." Here's what actually works: pick a 500-line radius around whatever you're changing. Understand that. Change it. Run the tests. If the tests pass, ship it. If they fail, blame the person who wrote the tests. (It's probably you from last year. That person was an