I have 2 sons in Universities in 2 different State; the following are some of the reason requires students to maintain Full Time status:
1) Majority of the Scholarships
2) Majority of the Medical, Dental and Optical insurance if you are on your parents plan.
4) Majority of the Auto-Insurance if you are under family plan.
5) Majority of the student aid and work study program, also you may have to pay penalty if you fall below the FT status.
6) Many of the on campus jobs.
Most Universities will grant exception only toward the last quarter / semester of Senior Year.
If you are not sure, register more then drop the class during the allowable time frame. Review your major curriculum and be familiar with it. Use your AP credits to the max not just to satisfy your core but electives as well. Look for double qualification in electives, that is one class satisfy 2 electives category.