The one interview question I can't stop asking.

Late in every interview I ask the same question now. "Tell me about a decision you made at work that you wouldn't make again." I used to ask about strengths and projects and what they learned from failure. Those answers are well-rehearsed. This one isn't.

What I'm listening for is whether the person can hold their past self at arm's length without being either defensive or performatively self-critical. The candidates who do that well almost always turn out to be excellent engineers. The ones who can't quite get there — who either deny they'd change anything or rush to prove how much they've grown — almost always struggle with the actual work.

I think the question works because writing good code is mostly the discipline of revisiting your own decisions. You wrote it on Tuesday; you read it again on Friday with fresh eyes; you change it. If a person can't do that with their own career, they probably can't do it with their own code either.

The other reason I like the question is that it's hard to fake. Behavioural questions reward preparation. This one rewards a habit of mind that's either there or it isn't. You can hear it in the first ten seconds of the answer.