Really depends on the HS. Even though the AP courses are supposed to follow the requirements of the college board, not every school teaches every element of the AP course or covers all the topics on the SAT 2. One example is a local HS (not the one my kids went to) that offered AP Calc BC but told the kids to take the AB test because the course didn’t cover all the BC material and kids did not do well on the BC test. In that instance, a kid that wanted BC credit would have to study on his or her own.
When one of mine took AP Bio, the course had recently changed. If I remember correctly, the teacher suggested the students not take the SAT 2 in Bio unless they were willing to self study because there were topics on that test that weren’t covered in the new AP Bio curriculum.