I find 30 minutes is the perfect time to take off and put back on. Some can go an hour under strong tension before a break. This gives opportunity to massage and get some angular stretching in, which will add to the gains you are already making. I like the half hour because I find this is when I start to lose a bit of
traction, in which case I can make fine adjustments at the base of the
SizeGenetics to continue the set or, as I stated, take off and recirculate stretch and start the next set.