Sorry, I should have said "trading firms", but they are pretty similar culture wise. Most hedge funds have internal funds as well and they run it similar to a prop trading firm.

I think in general though a small company (JS has 900 employees, so I'm guessing around 50-100 devs) simply can't hyper optimize their entire engineering stack to the same extent that a large FAANG can. It's far too wasteful. And I'm talking about tooling, infra, and overall process, not just the code. Code review is the minimum any competent engineering org should be doing.