We have a PTO policy that caps at a certain amount of hours, so technically it’s a rollover in that it’s always available, but if you hit the cap you don’t accrue more. Starting off you accrue around 5 hours of PTO per bi-weekly paycheck, and that number can grow the longer you’re with the company (I think the highest is 8 for being here 10 years). I believe the cap is 480 (roughly 8 weeks) so it’s easy to obtain and hold onto PTO. After our first year of employment, we are required to take 5 consecutive days off per year. Unfortunately this doesn't do much to combat PTO hoarders, but our HR department recently did away with the PTO payout policy. The only way to receive money for accrued PTO now is to leave the company amicably.
Honestly, it’s a pretty good system. A lot of people here from low-level to senior management take a decent amount of vacation time, and no one is really questioned about it as long as they have the PTO in their bank. My only qualm is that sick days are lumped into PTO (which, I do understand since it is a very generous policy).