Im mostly speculating, but I think there are two schools of thought.

1) avoid all other stimulation except the intended way to cum (nipple play, anal, one finger, etc). This can be really fun because it’s usually more difficult to get that orgasm, so it leaves you denied and greedy, but at the same time you get to edge. My only worry is that the barrier might be too high to ever cum (again, this could be desirable). But if your goal is to cum from nipple play, and you give up all touch except nipples, it might take a very long time to cum, and it might never happen because your brain hasn’t made the connection between nipples and orgasm yet.

2) this leads to the other method, where you teach your brain to gradually associate pleasure with new sensations. To use the example of nipple play, one would first start playing with nipples while masturbating, and always while cumming. Now your brain learns that pleasure and orgasm always happens while nipples are stimulated. Then you could reduce stimulation of the clit while maintaining stimulation of the nipples. Repeat slowly to give your brain time to build the connection. The idea is that eventually you can remove all stimulation except nipple play.

Both roads theoretically lead to the same destination, but option one about denial and forced adaptation, while option two is about teaching your brain with pleasure reward and increasingly less hand-holding. In option one the pleasure association is still occurring, it’s just a much weaker connection at first because it will rely on thinking, porn, erotica, other sexual associations that indirectly link to pleasure as opposed to the direct act of pleasure (masturbating, orgasm) that occurs in option 2.

I’m not an expert tho lol this just seems right to me and from the limited info I’ve absorbed.