Technically, today is Labor Day and I could have had it off, but I volunteered to work so I could take tomorrow off for doctor stuff.

So here in Italy you get 168 hours of holidays, which you have to schedule in agreement with your employer; then you also have 104 hours of leave, which you can take whenever you need to, and your employer cannot refuse them. At a previous job we also had, as a second level agreement over the national collective contracts, 10 hours of medical leave, which you could use for... doctor stuff.

edit: you don't HAVE to take your holidays, but most employers FORCE you to, because it's costly for them if you don't, they pay more taxes and may get fined