I just ask the individual contributors how much PTO they've taken in the past 12 months. It's more or less an open question, doesn't necessarily means I'm interested in taking too much PTO. You'd be surprised of how honest people are. I had interviewees even start venting about burnout. Someone from an e-commerce company (not Amazon) told me he's gonna take a month off as he took 0 vacation days for the past 1.5 years (!!!). He admitted he's probably going to get in trouble but he doesn't care anymore.