How much do different PE exercises "hurt" for those who've gained

I’ve been reading about different people saying that if you’re putting lax force into stretching or jelqing that your gains will be noticeably diminished, but also that many seem to say that they “feel” the different parts of their penis stretching and that they can tell that way.

Can anyone share a little on exactly how you respond to the stress, or at what point you say “that’s enough” in a stretch or in the firmness of a jelq?

*Edit* wanted to edit topic title, now realize I can’t, replacing hurt with discomfort **

Pain: bad. Some degree of perceived stress: good. Erring on the side of safety keeps your penis unbroken whilst you learn how much to push it.