I worked at a small firm once where an 18 year old joined and took full advantage of the "unlimited PTO".

He was taking roughly a third of his time off.

Fired inside 6 months, and amazed it took this long.

It reminds me of the Dilbert joke about asking to be put on 4-10’s and the boss replies why would I do that when I already have you for 7-12’s? With unlimited PTO, if you can only take it when there’s no work to do.. well in my business the work is never done. Demand outstrips supply so completely and consistently, it would be an impossible hurdle. I’ve worked in jobs where even limited PTO was near impossible to take beyond the occasional one or two days. Banked PTO was basically considered your severance package. Seems hard to set expectations correctly with unlimited PTO plans.