Florida public universities have a summer session requirement, even if the student could otherwise graduate in 8 semesters. So most students have to enroll for more than 4 academic years’ worth of course work (8 semesters plus a summer) unless they can complete all requirements in 7 semesters plus a summer.
This may have similar motivations as the spring admissions at some colleges. Many Florida public universities are only moderately selective, so many of their students may have difficulty finishing in 8 semesters. Having them take courses during the lightly enrolled summer session(s) (when there is plenty of extra capacity) is preferable to having them enroll an extra fall semester after their 8th semester.