My oldest taught herself Calculus out of the Saxon Math Calculus book when she was in 11th grade.
She spend her senior year in the local public high school and took AP Physics and the teacher had to tell her to not use Calc to solve the the problems cause it was AP Physics B and not A (or vice verse. Whatever it was, it was not the calc based AP Physics)
Outstanding. My son took multiple AP classes and actually taught many of them and did evening review sessions. He was far better versed in the subject than the teacher assigned to teach the class. He scored a perfect 5 on every AP exam. There was a motivating factor in all of this. His girlfriend was a straight A student and he needed to play at that level.