Filtering on anxiety levels doesn't mean you're selecting for confidence generally, it means you are selecting for people who are not anxious in the interview.

Filtering on anxiety levels doesn't mean you're selecting for confidence generally, it means you are selecting for people who are not anxious in the interview. If you practice for 1-4 hours per day for a month or more (as I did last time I was on the market) on a particular skill (like tech interviews), you become more confident at that thing. Grinding tech interview practice works, which is not great, for either side, because it's mostly orthogonal to actual job performance.