My high school AP calc course started out somehow getting behind in the first week. After that, the teacher kept assigning homework for material we wouldn't even cover until the day it was already due to be turned in. It was pretty brutal for someone like me who was accustomed to coasting through all of my other courses.
I took a bit more math in college. It wasn't easier; the professor simply kept pace with the material. If you needed help, you had to go to a TA or the professor out of class hours (an option that wasn't really available for a high school setting).
I can easily imagine that many students who were exposed to college level math for the first time in one of those courses would flounder and drop out (though I didn't witness much of it myself).
I took a bit more math in college. It wasn't easier; the professor simply kept pace with the material. If you needed help, you had to go to a TA or the professor out of class hours (an option that wasn't really available for a high school setting).
I can easily imagine that many students who were exposed to college level math for the first time in one of those courses would flounder and drop out (though I didn't witness much of it myself).