These reports of 20-30lbs of gains in 30 days cant be lean muscle tissue. It takes months and years to gain this tissue IMO.
How much did people really keep after stopping Superdrol that put on a lot of weight?
Back when I was 22 years old and first started serious training, I put on 41 lbs (going from 167 lbs to 208 lbs) of mostly lean tissue in exactly 12 weeks...100% DRUG-FREE. Yes, those gains are extremely uncommon, but my circumstances were also highly unusual. While I had done some lifting in high school I mostly only bench pressed and did some curls. I never weighed more than the upper 160's. Leg training was basically completely absent, as was back and delt training. However, between the ages of 14 and 22 (I started the above-mentioned 12 week training cycle at 22), I accumulated a large body of knowledge regarding the proper application of bodybuilding principles. At age 22 I put it all into practice. I did not progress in knowledge and physical development in parts, like most people who learn as they go. Rather, I transitioned from what was basically a non-training individual, to a full-time bodybuilder overnight. I applied 100% dedication and effort to my training, diet and rest. I didn't miss a single meal, training session or minute of sleep. The only supplements I used were creatine (which assuredly accounted for some intramuscular water retention) and a product called Mega-Mass 4,000, which was total crap, but supplied me with a lot of calories.
The point here is that the rate at which lean tissue can be synthesized is dependent on circumstances. There are many people out there who, under the right circumstances, have added lean tissue very quickly.
If I was able to add 41 lbs of mostly lean tissue in 12 weeks as a drug-free trainer, I have no doubt whatsoever that, under the right circumstances, an enormous amount of muscle can be gained with drugs.
As a side note, after that initial 1 week period was over, I proceeded to add another 22 lbs of mostly lean tissue over the next 9 months (drug-free), providing me with a net gain of 63 pounds in my 1st year of drug-free training.