I gained about 1/2" in girth jelqing for about 1 month about 4 times a week, but no length gain which is what I was after. I did more jelqing than a month though, just I got my gains in that first period then it didnt gain in the additional month or two I did after that and I stopped.
I can fathom how you could gain girth from doing it, but not length, but people say they get both... I did not...
Frankly though, ya gotta have a lot of time and privacy on your hands to do it properly and regularly, and I dont have a lot of either.