The biggest mistake people make is not dieting on juice. Sure, take 4 weeks to get your weight up, but after that, clean up your diet and start rotating your carbs, add in a little cardio. You'll find that if you do it slowly enough (especially with a little growth added) you'll just start hardening up at the same weight. Guys reason that they aren't yet big enough to cut because they think they'll have nothing left at the end of it, when you actually put on the most muscle during a contest prep phase. Don't get me wrong...you need to loosen up the diet and just train hard and heavy, but not for very long, because seriously, the amount of muscle you put on after just the first few weeks is gonna be really insignificant. Hence the reason these guys juicing like Squadfather's talking about year round remain 190 and just don't develop the sort of muscle maturity that would lead them to look like actual bodybuilders. I think it has something to do with some sort of orthostatic set-point your body depends on related to blood pressure to determine whether or not adding more muscle tissue is a functionally-viable option for it's increased performance.
I don't think many people realize how many people are actually on shit or have been.
You can put on muscle on a precontest diet but it depends on a few factors. For example: if you have been clean when you start your prep you can add some LBM, most of which will be water due to creatine levels going up, blood building effects of the steroids etc. In your example adding GH will increase water stores further so it's a bit deceptive. But if you have been on shit a couple of months already it's pretty hard to switch to a calorie deficit and continue adding muscle. It's pretty hard to put on any appreciable muscle in a deficit since muscle doesn't form out of thin air. It requires energy and protein.
I do agree with what you have said about dieting in general, that it's very beneficial to diet down once a year or so. If you use a bunch of drugs you may be able to maintain a lower BF% when you start bulking, GH excels at this.
