I too have hair on my shaft now, but I can’t remember whether or not it was always there or if I just noticed it because I’ve been paying closer attention and have heard it mentioned by other people on the forum.
As for my dorsal vein I can absolutely confirm without a shadow of a doubt that it’s branches have progressed along my shaft.
The vein on the left side was originally more pronounced (quite large, and shaped — if you excuse the metaphor — like a ‘fat little grub’). It was so pronounced it immediately got my attention as soon as it emerged from my fat-pad and I didn’t even realise at first that I also had one on the other side.
At first it would appear and disappear in and out of my fat-pad as I PEed, until it eventually stayed put outside of the pad (curled around the shaft against the fat pad). It was around that time that I noticed I had one on both sides. Eventually they caused me to increase my base-girth measurement (I used to measure it with the tape measure just lightly wrapped), but they kept progressing until I had to reduce my base-girth statistic and post an apology and explanation for the stat-reduction (it’s nothing to do with the link in my sig— that’s a second more recent stat-reduction due to the fact that I’m measuring base-girth with a much tighter tape-measure now)).
They seem to be a little less pronounced now and I think they may have become a little elongated but the amount they’ve moved corresponds with my gains (in fact they seem further up the shaft than my gains suggest they should be.)
The diagrams I’ve seen suggest that the first branch on either side is more pronounced. I’m not sure to what extent that might be artistic licence or if that should be taken as an indication of absolute fact, but basically the only two I’ve noticed (one on either side) or have ever really been able to discern seem to be the first branching (also the branch on the left side is more pronounced but I’d imagine that’s just co-incidence)
I’m preparing a post that summarises the best advice I can basically give anyone on hanging and put the following pictures together for inclusion in the post to illustrate my view of what might cause gains (I find your suggestion that there might be a weak point where all the production takes place to be very interesting— do you not think it’d end up becoming conditioned and therefore unable to yield ongoing gains? I’d assumed from what I’ve seen of my own veins that the gains may be more or less solely due to the pulling free of the inner penis).
Here’s the picture (if you have feedback on the picture or any of the above I’d be very interested):