Pump for 20 minutes, rest for 10 minutes, pump for 10 minutes, rest for 10 minutes, pump for 10 minutes. So the whole"session" lasts an hour. I believe it is supposed to simulate cluster feeding and boost your supply. I do it a couple nights a week after DD has gone to bed.
Re: what is a power pump?
Eh, interesting... but doesn't that hurt or make you feel sore?
I've heard some strange stories about pumps.