"I always find it hilarious that the pre college education in US is so messed up. Instead of doing Algebra 1, Algebra 2, calculus, geometry as one subject that you do in a year and then completely forgetting about it till the next time you have to do it, how about you do a little bit of everything every year from grade 8-12. Problem solved."

In my experience, each year built off of the previous and implicitly provided a refresher.