A good student will need no more than 5 years to get a PhD. Those taking 7 to 12 years are in the humanities where the whole point is to avoid real work and to stay in college as long as possible.
But that would mean the little darlings would have to take classes at 7 a.m. or in the evenings or they'd have to go during the summer. That's so unfaaaaaiiiiiirrrrrr.