Learning math is cumulative, so it is not helpful to blank out previous materials. Sometimes, it seems that students want to learn to pass the "next test" and I don't think that is a good approach. Whenever you take more advanced courses, it would be a good idea to review previous concepts because they all build on one another. It's time-consuming, but it's probably more beneficial to you in the long run. Just my opinion, and I have been out of college for 40+ years, but the cumulative basics for math studies probably haven't changed much since then. Good luck.Every semester, whenever I begin to learn a new subject, that is, a more advanced class of the previous subject (i.e. algebra -> pre-calc -> calc -> diff eq, etc.) I forget a lot of the stuff I learned in the previous class when I'm learning the new content and constantly have to review all the time because I keep forgetting the basics and it's interfering with the more advanced classes...is this normal or should I hammer the bases more into my head so I will never forget them and not have to look back every time I need a formula or theorem and whatnot?