Expectations may differ from how much time is in a traditional PTO bank but at least in general, it's OK to take accrued time off barring special circumstances.
We got bought out and the new overlords announced they were going to give us five weeks of vacation. There was actual laughter in the room. We can't even use 2 weeks, what's 5 gonna do for us?
When I put in my two-weeks at my last job, my boss said that if I can get all my work transferred in only a couple days (I did, since I basically had almost no work, hence my search for a new job), then I could just fill the rest of my two-week notice time with my remaining PTO. No reason to spend two weeks pretending to work at my computer.