If the primary function of schools is to babysit and accomodate parent schedules, then all breaks should be done away with.
If the primary function of schools is to provide a steady routine for athletic teams, again, do away with all breaks.
If the primary function of schools is to teach and educate kids, year round school makes sense. Virtually all of the current educational research indicates that a calendar with moderate breaks throughout the year and a shorter summer break is much better for students in retaining what they've learned the previous year, and the breaks through the year do serve to refresh both students and teachers.
It is unhandy for athletics, though. Basketball has been having to live with a break for decades. Now it's lapped over into fall and spring sports and impacts virtually every team in a school.