Defined PTO is easy to turn into "use it or lose it" which effectively forces people to take time off, which is a major issue in the US - people need to take their allotted time! The best system would be one where once you hit "lose it" you start getting cash instead, but that would cause other weird incentives.
You then have managers that are flexible with your defined PTO, and let you "go negative" a certain amount. As long as people don't abuse it, it works well. Some companies "dump" your year's allotment of PTO on Jan 1 so you can work it down instead, same idea.
Defined PTO is easy to turn into "use it or lose it" which effectively forces people to take time off, which is a major issue in the US - people need to take their allotted time! The best system would be one where once you hit "lose it" you start getting cash instead, but that would cause other weird incentives.
You then have managers that are flexible with your defined PTO, and let you "go negative" a certain amount. As long as people don't abuse it, it works well. Some companies "dump" your year's allotment of PTO on Jan 1 so you can work it down instead, same idea.