While the format of AP courses is that of high school (as opposed to college), the material may overlap with frosh-level college courses, depending on the specific course, high school, and college. If the college allows advanced placement with an AP score that the student has, it would be a good idea for a student who wants to continue to more advanced courses to try the college’s old final exams for the course that may be skipped to see if s/he knows the material well by the college’s standards. There is no reason to waste time and tuition repeating what one already knows well, but one should be sure that one knows the material well before going on to a more advanced course.
Remember, lots of students have tight enough financial constraints that make graduating a semester early or avoiding graduating a semester late a significant factor in college affordability. Actually, avoiding graduating a semester late may be the bigger financial factor, since semesters beyond 8 may be significantly more expensive due to scholarships ending and/or financial aid getting worse. Remember also that shaving off a year of college with AP scores shaves off the frosh-level stuff; the student still needs to complete the junior/senior level course work that is the most important part of the bachelor’s degree and where attending a four year school provides most of its added value academically (frosh-level courses are commonly available at low cost at community colleges). So a student who does use AP scores to graduate early is only losing the lower academic value part of attending a four year school; s/he will still experience the higher added academic value in junior/senior level course work.
In the absence of such financial constraints, the use of AP scores to take advanced placement in a course sequence (contingent on verification with the college’s old final exams of the course to be skipped) or fulfill side requirements (e.g. general chemistry for a non-chemical/biomedical engineering major) can allow the student extra schedule space to take free electives, which can include either additional advanced courses in his/her major (i.e. more opportunities for breadth or depth within the major), or additional out-of-major courses of interest (i.e. more opportunities to get a broader education generally, or get additional depth in an out-of-major subject).