I worked at a company that had unlimted PTO when suddenly one day they revoked the policy because they said some people were abusing it. The new policy was still very generous (6 weeks PTO per year) so no one complained. Fast forward a year later and we were hearing things from executives and managers like, "you know you don't have to use all you're PTO, right?". I'd ask, oh, it will rollover to next year? The reply: "No, it won't. But that's really the wrong way to think about it."

So it turns out people were taking much more time off now than when PTO was unlimited. They started denying request and making up trivial rules, like 2/3 of your team must be available at any time (regardless of the team size), oh, and those rules weren't in the official policy. Good luck trying to get specifics in writing.

Eventually they changed back to an unlimited policy but secretly told managers they should start denying requests after x number of days have been used. I think it was five weeks, which again is still generous but it bothers me because the intent is to hide that number in hopes that people will use less. I also get no tracking for how many days I've already taken unless I go through my requests and count the approved ones myself.

The unlimited policy is definitely a scam at many companies. Most of my team has been denied requests for reasons that don't exist in the written policy, like, "you recently had PTO already." Honestly I'd rather have a policy that only allowed 3 or 4 weeks with a minimum mandatory that each employee is required to take at least two weeks off per year.