Here is my take:
The amount of potential length gain from stretching ligs varies. How much you stand to gain from it depends on what you’re starting with. If a guy’s existing shaft length is initially constrained by tight ligs, stretching them will result in more length expression of the shaft, this being independent of any actual shaft enlargement that also occurs. You’re simply freeing the shackles.
Is the shaft sticking out farther and measuring longer than it did before an illusion? No.
Some (probably relatively few percentage wise) begin with a substantial amount of existing length held back by ligs, which is why they gain extremely well from lig stretching exercises or even surgical severing (yuck!). Others won’t get any length gain from stretching or severing ligs because their ligs weren’t a limiting factor to begin with. Most likely fall somewhere in between.
I think that when your ligs have been stretched enough to no longer be a limiting factor, focusing effort on stretching them even more isn’t productive.
Hanging may work deeper supporting structures in a way that allows for some more existing shaft length to be expressed. I’m just throwing this out for speculation. The anchoring down there is pretty stout, but who knows?
Gains from PE come from a combination of ligament stretching and the shaft itself enlarging.
I stretched the hell out of my ligs. The ligs that surgeons would cut are not a factor for me. I would not gain anything in length if they were to be severed today unless I were to cheat on my standard measuring method (ruler on pubic bone, penis straight out). Of course, I could do that without surgery. My erection angle dropped a little from PE, but it was quite high to begin with.