A statement I usually rift on, is as long as you are getting a good stretch, you should be fine.
I have read from different sources that you generally want to stretch your penis so that you are 1 inch longer than your optimal erection size. I personally can't do this and have the
SG stay on for more than 15 minutes, so I can't say for sure if this would be applicable to everyone.
For me, a good stretch means after having the
SG on for an hour, that my penis starts to feel pain. That was the case when I first started wearing the
SG, anyway.