The research indicates that GH's primary impact is to change lean body composition, not as a mass builder. But what it does do is allow high level trainers to use large doses of steroids and to consume copious amounts of food without getting fat or smooth. That's the unique talent of GH.....you can get big AND lean at the same time.
The research seems to indicate that massive doses of GH are a waste, also. Our natural defense mechanism causes exogenous GH molecules to be "bound" at a higher rate, which prevents them from interacting with the GH receptors which require "free" GH molecules. I have used 12iu a day for 3 months, and didn't see a lot of difference over 6.
I'm going to attach a couple pictures. In both, I am using the same dose of GH. In the upper, I was looking for hardness, and used light insulin with mostly anabolics, and a strick diet. In the lower one, heavy insulin and mostly androgens and a lot of calories. I think you can see which approach builds more mass.