My kids took 32 AP exams between the two of them. I paid for 31 of them. Son took one of the computer exams on a self study basis – really between computer camps and coding for fun he studied for it by just being him – because our school didn’t offer it. Took him to a nearby high school that did offer the test and they didn’t charge us to take it.
They got a mix of credit and no-credit out of them. Started college as officially juniors in terms of credits but not toward graduation. Daughter could graduate early but she has a full ride that can’t be used for grad school if she graduates early so no real reason to graduate early. Will get double major instead. Son could also graduate early but will likely pick up some graduate school classes at the end of senior year.