depends on how long you want to be "shut down" for, have your liver be stressed. i'm sure there are people who have run a ps/ph that long but after four weeks or so most stop noticing gains, therefore they come off and start pct. look @ SD, most stop after 3 weeks, hdrol, most run that for 6 weeks (i am one) but epi (i only run it once) most of what i've heard was/is 4 weeks is time enough.