Can't speak for the US, but in the UK unlimited pto made zero difference. If anything pushed numbers up since you've still got the legislated 28 day minimum setting a floor while unlimited (theoretically) opened up the top
Having the "You have X hours of PTO" made the expectations clear. Especially for less senior people who might not want to rock the boat or seem greedy. And while use it or lose it policies are overall bad, they do push people to take breaks instead of "saving it up for something good/important".
It also heavily depends on management. There's definitely some companies that do "unlimited w/ manager approval" with the manager expected to find ways to deny and those are 100% shit places to work, but not everyone gets a lot of choice on that.
With the constant stream of projects there is no opportune time. On top of that management rarely works vacations into capacity planning, so if you leave it just gets dumped on someone else. You are then disincentivize to take days, because your coworkers suffer for it.
>your coworkers suffer for it.
Yeah that's the cultural difference right there. People just go on leave whenever. If the company is so fragile that it can't survive someone being away for a bit (or sick) then it's inadequately staffed to be resilient.
That said I'm in an industry where replacing someone takes ~6 months so probably above average cautious on resilient staffing
>Are you required to take those 28 days?
Legally - don't think so, but the question just doesn't make sense in that context. Everyone's taking all their leave from what I can tell.