This is just my opinion, but to me it depends on what’s causing the growth. If you’re gaining from ligament stretching, that’s different than gaining from tunica growth/expansion. Gaining from increased EQ is different from both as well.
I mean to me it seems like there has to be an increased ability to expand. An erection is internal pressure right? Like a balloon. You either need more pressure to expand the balloon or you can stretch the balloon or you can change the structure holding the balloon in.
On one hand I’m hesitant to relate it to the hypertrophy that bodybuilders are experiencing. At least not hypertrophy in the same sense. In other words I’m hesitant to apply bodybuilding techniques regarding on/off days. This is just because I see PE as atypical so far as we are not using forces our body is structured to inflict. I mean our quadriceps perform a function. Targeting the quads while weight lifting means performing that function with sufficient weight and sufficient repetition to cause hypertrophy. With hanging, the force is not something our penis typically experiences. Clamping comes close. Pumping…I mean it’s similar but again, not normal in terms of typical function. Jelqing is again, somewhat normal if you consider changes of internal pressure during sex and gaining of erection, but still our penis doesn’t move blood through itself that way normally.
On the other hand from my limited experience, it would seem rest days make sense. Intuitively I’d think rest days that have some gentle encouragement towards expansion or stretching, just enough to maintain whatever signal is telling the body to adapt…but not enough to put it in defense mode.
It’s all speculation on my end though.