I've got managerial experience hiring (on both ends of the spectrum of talent) and engineering experience in computational finance at a prop firm similar to Jane Street. He has a fast-hire ability and high-signal to noise for sure but he works at a prop firm. His hiring practices are a market anomaly simply because he can pay effectively whatever a competent developer wants. Jane Street can basically throw money at the problem. What you have at a 'normal' company is a real difficult time finding someone who can tell me when to use a lens and when to use a zipper in Haskell who are actively looking for employment.

Anecdotal but I casually attend Boston Haskell and I can't remember the last time someone was out of work other than 'funemployment' (e.g. a startup goes bust and they have accrued more than enough money to just sit around, stretch and work on pet projects). The second they 'need' a job, they'll casually mention it and I think ~3 out of the ~7 times this has happened, someone in the crowd went like "oh Bill, yeah come in to <his office> Monday and meet our CTO". No recruiters, no wait. The CTO trusts Joe has heard Todd ask enough insightful questions consistently enough that he's going to be a good hire. Tuesday 9AM HR, 10AM pull the repo down, setup stack, start poking around Haddock and start closing the easy tickets. Good talent (10 of the 15 applicants are quality) might respond to Minsky but those other 9 guys will be picked up almost invariably in well under two weeks