I have had been through unlimited PTO since 2009. On the surface it feels like a win-win for the employee, but underneath it hides some tar pits.
1. In America, if you queued up your PTO and you leave for another job, you are owed your back PTO. So if you have four weeks and there is some minor hold back, and you leave the company at the end of the year. You lose one month's pay.
2. Companies no longer have to hold back an asset for PTO so it reduces labor costs.
3. Companies can set schedules for a worker to be 48-50 weeks of solid 40 hour weeks or even higher, and if the employee doesn't deliver his review will be held accountable
4. Take a high performer that starts to utilize UPTO, he won't be deemed a high performer even if he achieves his 40 hour goals in 40 weeks, and straddles the other 12. He will be deemed average to above average as folks will remember the 12 and not the 40.
UPTO is a bigger benefit for companies than the employees.