As in, it's certainly not a standard 8-5 job of 40-50 hours per week. Is it common (and expected) for them to sometimes put in 80 hours a week, and to occasionally put in 10 hours? (say, during times of personal crisis or of particularly intense coursework?)
It depends on you. If you really want to, you could probably have quite regular working hours (except for the odd deadline). I would say that 80 hours a week is excessive and if your advisor expects you to do that, then you should think about changing your advisor/course.