I've thought about this on occasion. Anecdotally (and subject to selection and confirmation biases) I've seen students who struggled excessively in a given cour

I've thought about this on occasion. Anecdotally (and subject to selection and confirmation biases) I've seen students who struggled excessively in a given course, dropped, and taken the previous course to excel not just in the subject they originally dropped but also in subsequent classes. I've wondered if my alma mater might be better off recommending students to start a level or two below where they currently are to fill in some of those vital gaps.