I would like to add something about pumping. As a premise, I don’t think pumping is the best technique for permanent gains, for most of people. But there is for sure a percentage of people who gets permanent gains from it. So said, pumping is probably the oldest PE technique. I can remember vacuum pumps being advertised in popular magazines at least 30 years ago, while I think jelqing is born on the web. So I think there has been more experimenting with pumping than with any other PE technique.
Now, while it’s true that pumping is a different beast than stretching, that there are other tissues involved, etc., if one is interested just in gains, and wouldn’t mind a more or less severe ED most of the times (there are people like that here, and they are not a small minority), that wouldn’t make a difference : overworked or not, the penis will inflate under the vacuum, so if high pressure for short duration was the best for gains, that’s what expert pumpers would advice.
They do not, and if you write that in numbers, it will be good stuff to think about : even a newbie pumper will not have an injury (if you don’t count discoloration as an injury) pumping at 15hg for 15 minutes; I think even 20 hg for short duration wouldn’t cause an injury to most of people. Well, what pumpers who had gains suggest, is to pump at 5-6 hg vacuum. There are guys who like to go ‘hardocore’ with pumping not minding the insane fluid retention. They anyway, when asked, as far as I can remember, always suggest low pressure fot lont time, if you are interested in permanent gains.
Now, is that true for all the people? Probably not. Like in weigth lifting, there is the guy who puts on tons of muscle doing one set per week, another can train everyday without ever going overworked etc.; there is just too much variability in human things to say that anything holds true for everybody. We look at the trends. We know trends reading members’ posts - which is not controlled material, so to speak, neither a well built sample. We know these limitations. So we can’t have certain proof of anything. But if anecdotal reports seem consistent with what the research tells, than that is good sign.