Bigbychoice,
You speak with a very authoritative tone in your knowledge of how all these guys trained. What do you say to the people who personally witnessed Viator and the Mentzer brothers training just as advertised back in the 70s?
No, they didn't do one hard set per body part and run from the gym for weeks on end before coming back

Mike told me his best gains were from training each muscle roughly thrice in a two week period, a'la Frank Calta's split. Mike said he averaged from 3-6 failure sets per muscle group. Dave Mass was witness to these sessions and could confirm what Mike said. If the late Keith "onlyme" were still here, may God rest his soul, he would confirm that Ray was a HIT fanatic.
Did Mike, Dave and Keith all lie? To be sure, Casey DID go super-volume for the Olympia he should have won ('82?). He explained that to Brian D. Johnston in an interview 20 years or so later, noting that he (Casey) thought it was necessary to "grossly overtrain" to get the cuts needed to win an Olympia in the post-Zane era.
There is also the fundamental question: what IS HIT? Back in Tom Prince's arrogant, drug-induced heydey, he once said, "I talked to Dorian, and he said he didn't 'do' HIT." Setting aside the fact Tom was a Nubain addict and notorious liar, even if we take the quote at face value, AGAIN: what does HIT mean? Dorian obviously trained according to most definitions of high-intensity training. If he really said that to Tom, could Dorian have meant he didn't do the old Art Jones routines?
Context, context, context.
Before anyone says I think HIT in any form is some panacea, no, I certainly do not. Various forms of it worked for me, but before I got sick, I wish I had experimented more with other methods. I recognize the utility of higher volume, very heavy training and I know that, when I was "enhanced," Gironda-style lifting was also useful. I was gravitating toward some of the latter before my illness and I liked it for shoulders and arms; sadly, the experiment was cut short : /