I have Arnold's Modern Encyclopedia of Bodybuilding and devoted one summer to doing this routine. This is his advanced routine, he actually has another routine above this that he used while in season.
I did it for two months and it kicked my ass. The last month of my summer I broke it down into a 5 day program. I came out of it bigger and much stronger but beat. The routine is made for someone on steroids, of that I have not doubt. It is a six day a week program that takes a lot of time in the gym.
It can be used by anyone.....
Steroids increase strength/recovery between sessions. A natural trainee p would just have to make sure his sleeping/eating is on point and take off an extra day or two here or there when they feel run down, it's all common sense. People act as if you can't train 5-6 days a week unless you're on steroids, most end up under training actually and still look the freakin' same a year or two later. Everyone has a certain volume they can handle and work capacity, if you're not aiming to put yourself out of the comfort zone most of the time you're in the gym, your body doesn't grow in strength/size bottom line
If you're going to try it, I suggest you devote a lot of time to it. Luckily, when I did it, I had a lot time to eat and sleep to recover. You will need to sleep a lot and eat a ton. But if you can manage it, you will come out bigger and stronger.