I stopped sending thank-you notes after interviews and started sending one paragraph of the answer I flubbed

Thank-you emails all read the same and I doubt anyone finishes them.

What I send instead: the one technical thing we ran out of time on, or where I clearly didn't land it, written out properly. Usually after reading up on it that evening.

Last month an interviewer asked how I'd stop a queued job from being processed twice. I said something about a flag in the database and moved on. The instinct wasn't wrong, I just couldn't say where the flag comes from or what happens when two retries land at the same moment. So the note I sent said what I'd have said with more time: a caller-supplied idempotency key written under a unique constraint, so the second attempt loses the race on the insert and gets handed the first attempt's stored result instead of re-running the work.

One interviewer brought it up unprompted in the next round. Another mentioned it weeks later.

Takes fifteen minutes, on an evening you're already replaying the whole thing anyway.