My brain stores it away in a magic database that cannot be queried in any useful way. If I say say "brain, give me a list of learnings from projects you have worked on" - it returns an empty set. But if I'm reviewing someone's code, my brain suddenly pipes up and says "hey, I smell bad code, this is poorly designed and will not perform well - just like that time 7 years ago in a previous role when you smashed your head on the desk for hours trying to get to the bottom of that legacy spaghetti code slowdown"