10 max. You'll hear a lot bullshit even dudes showing vids hanging more....of course for 10 sec. max...truth is after 10 pounds the pressure will only do harm.
How about this: Skip the hanging BS (and trust me I was involved since BIB days, even helped him design that pos hanger) and stick to the science. Only one thing has been scientifically proven to make your penis larger: traction.
Save your money on these vac hangers or any hanger at that. Follow the studies.