We have this at my workplace. Before it was "entitled to X days per year and can only have Y in the bank" which everyone was loath to waste, i.e. would take ti

We have this at my workplace. Before it was "entitled to X days per year and can only have Y in the bank" which everyone was loath to waste, i.e. would take time off just to not lose it, and of course the company has all that untaken, unexpired vacation time on the books. Now it is "flexible PTO" which in practice means, use the same days you would otherwise have used, minus the "take them just to not lose them" days. You still need to be responsible as far as work obligations go, i.e. the boss needs to say OK. Works fine. On the minus side, I take fewer days off, on the plus side, if the weather is nice and I just want to go for an all-day outing in mid week, and work won't suffer, I just go, without considering the vacation numbers i.e. there's no incentive to save them until just before they expire. I'm not aware of anyone who has used this to take more vaction than they would have had under the old system.