Solid post 
Do you feel insulin and growth hormone play their roles as well ?? For instance, isn't gh supposed to create new muscle fibers ? Perhaps one could use gh as a bridge ?
Yeah, the Growth Hormone is so anabolic in combination with AAS because it creates brand new cells, whereas AAS just makes the cells bigger. So, again back to the baloons. With AAS you're blowing up the balloon with concrete.. but then what if we added new balloons and blew them all up at the same time....
Insulin just shuttles nutrients extremely quickly and efficiently into the muscles eliminating the limits to which the muscles grow that exist even just using AAS alone. It's insanely anabolic. Following the balloon analogy, in a way you're increasing the balloon's capacity to hold concrete and making it bigger at the same time, creating a gigantic muscle. In combination with AAS and GH, training a couple days a week as you normally would naturally, and a ton of food. Well, you can get pretty big in the span of only a few months even.
A lot of the pros built all the competitive size they all have in less than 3 years. 5 years is a good solid number for continuous use of all these compounds. They then essentially maintain that size with elevated testosterone on a regular bases (Test in any of the available esters) and add the hardeners during the "cutting" phase because those DHT derivatives dry out the physique due to anti-estrogenic nature (they don't aromatise, so you don't get the bloat etc) and harden it in a different way than simply running Sustanon alone would (DHT is way more anabolic than Test). In 5 years they were already big enough that the additional mass didn't really matter. Just look at a lot of guys like Dexter and Jay.. they've looked the same for decades. Sometimes bigger and less conditioned. Sometimes a little smaller. But, essentially look the same to a non-trained eye. Those who grew slower, either had a slower genetic response, or didn't use enough.
(edit here: should also add that just like with natural training, with AAS of course you get the freaks like Ronnie who genetically have the capacity to blow up better. And this is where genetic response to drugs comes in. This is the core of pro bodybuilding. genetic response to the drugs in whatever combination that proves to be the most anabolic for you along with the food intake... but anyone can eat... and yeah, the training... but anyone can train. Then of course you factor in the genetic shape of the muscles, insertions and all that jazz that makes you look better than your friend, when you're both natural and untrained anyways. Just genetic variations in the joints, muscle shape andinsertions and skeletal structure).
So in summary:
AAS: Bigger cells
GH: New cells
Insulin: Considerably bigger cells, with added capacity for new size
When you understand why these guys look the way they do, you look at pro bodybuilding with completely different eyes.