Mentzer and HIT principles is in my opinion the best way to train possible, TO A DEGREE. However, Mentzer got carried away with philosophy and much of HIT eventually turned into more of a marketing scheme than solely a system of training. I believe in Heavy Duty part 2 Mentzer eventually advocated training only 1x every 9 days!! In his beginning literature it was more realistic and practical. Mike was also against cardio, so tell me how only working out once every 9 days and no cardio would keep you conditioned? And how do you even stay motivated enough to diet right when you're only in the gym every 9 days? It's like why the fuck even work out?
Mentzer didn't train like this until he got with Arthur Jones, and even then he would sneak off and do additional sets. Now, I am a huge Jones/Boyer/Viator/Mentzer fan, but there was a lot of garbage that went around during this mission to debunk volume training. Arthur Jones only admitted to Sergio Oliva being the only steroid user HE EVER took on to train down in Florida, and he stated that everyone else promised him they'd never touch steroids....which you and I know is all bullshit. The whole Colorado project with Viator was also a bunch of bullshit, and claims of a 63 lb muscle gain in a couple months is just ridiculous, and no credit was ever given to muscle memory and the fact he was recovered from a car accident and packing on muscle at an alarming rate, and probably taking steroids to the curb at the same time.
Mentzer was knowledgeable, but no Wizard. He was very good at talking/manipulating and convincing, which he got from Arthur who was basically his main influence once he got with him. But in all reality, Mike Mentzer was a know-it-all asshole who most people didn't like to be around, not to mention almost homeless because of a horrible addiction to speed, which I'm sure didn't help his "genetic heart condition"
Mike was good and without a doubt should have taken the 1980 Olympia, but Mike wasn't marketable to Weider. The Weider's hated the Mentzer/Jones click because they didn't preach supplements and really didn't believe in them. Joe realized that selling barbells and DB's didn't bring a lot of repeat sales, but supps did. He couldn't use Mentzer for anything, which is a reason I also respect Mentzer. Arnold was just more personable, everyone wanted to be like Arnold. But with Mike, it was his way or no way.