There is nothing magic about hanging. As marinera said, it may work great for an individual, or it may not work at all, just like anything else in PE.
I think it is a very big mistake to assume that length gains are “guaranteed” with hanging. It is also a mistake to assume that what has worked for you will work for anyone, and if it doesn’t they just haven’t done it right.
Bohm makes a very good point. Most people don’t take up hanging unless and until their gains from manual exercises have plateaued, and at that point the “easy” gains have already been exhausted.
I also disagree that combining hanging with other PE techniques is “counterproductive” I have yet to hear one cogent argument that would explain how it would be.
For myself, I have hung for a little over a year and have gained maybe .5” in length over that time. But I continued manual stretches and jelqing during this time, so I can’t say that even that gain was due to hanging. I had gained about an inch in length before I started hanging, however.