I think in some ways Pre-Calculus is the course that varies the most because it is often a hodge-podge such that two courses with this same name may not even touch on the same topics. In my day, Pre-calculus was only one semester so that the second semester was AP Calculus AB. You are correct that passing the AP Calculus BC exam meant that you could skip the first two semesters of college calculus. I think that my old high school's practice of stretching it out to three semesters made it accessible to most of the students in those classes. Regarding AP Physic C, I think our district offers the option of taking just Mechanics in one year or both in one year. I finally see why some seniors graduate with a crazy number of AP credits.