Here's a scenario every team has lived through: a critical bug gets fixed under pressure, everyone breathes a sigh of relief, and the fix lives only in one engineer's memory. Six months later, a new hire trips over the exact same issue, burns two days rediscovering what was already solved, and quietly wonders why nobody warned them. That's not a knowledge problem — it's a documentation problem, and it's shockingly common even on well-funded teams with mature codebases and experienced engineers who really should know better by now. The engineers who write a short, honest note after every real incident — what broke, why, how it was caught, how it was fixed — aren't doing it for credit, and they're definitely not doing it because anyone asked them to. They're doing it because they've personally been the person re-solving someone else's already-solved problem at 11 p.m. on a Friday, and they'd rather not do that to the next person either. It costs ten minutes. It saves days, sometimes weeks, across the lifetime of a project — and it's one of the quiet habits that makes a senior engineer's presence felt on a team long after any single fix is forgotten.