One other thing that Thibaudeau said in the first video about that myofibril protein synthesis (MPS) driving hypertrophy. He said that naturals had to work out more frequently than enhanced trainers to maintain MPS. However, there was a study conducted a couple of years ago on the effects of equal-volume resistance training with different training frequencies (once or twice a week) in muscle size and strength in trained men: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016534/ The findings were not consistent with Thibaudeau's premise. Although the study made a case for working each muscle group only one a week, and I have experimented with this frequency for some time in the past, I presently favor twice a week since I have whittled my workouts to bite-size sessions of only ~20 minutes each. The workouts are wall-to-wall intensity, but they're over soon after they've begun. So, for better or worse, I find myself somewhere between Thibaudeau's theory and the study's findings.
His premise is nonsense. A natural trainee needs to always guard against overtraining. That is the advantage to the "enhanced" trainee, their recovery is superior, making overtraining nearly impossible. Basic fact.
The entire body works as a unit. Stressing muscle groups separately taxes the entire body. You but one digestive system, one nervous system etc. If one has been around long enough to remember when AAS first came onto the scene, full body workouts was the way to go. Once AAS were plentiful the split routines caught fire. Why? Because the AAS allowed for longer workouts with quicker recovery. Thus you could have marathon push or pull sessions and recover. To do those marathons in the same day was too time consuming. Weight training used be physical culture. That's mostly gone.
I share you view presently. When I started out in my late teens with whole body workouts I made impressive gains despite too much volume and frequency. But despite my brimming with youthful hormones at the time, I still managed to burn out after several months. Too many hours three times a week. Youthful enthusiasm, and all that. In university and during my early work life, I still worked out, but I got more into rep volumes doing only (improper) bodyweight work. You wouldn't believe the numbers I could do for chins, pull-ups and push-ups, but it was all kipping and bad form. I was strong and lean, but I lost much of my size. Fast forward to my early 30s, I made some impressive gains in strength and size with an ABA BAB split using weights again, still working out 3 times a week, but on a split. Looking back, still too much volume, but I was ~young enough to digest it, and I continued this regimen well into my 40s, at which time it became too much. (And so, I must admit that the split served me very well in those days, as results go.) Then I went to fully body work with the same exercises and less (but still too much) volume, twice a week rather than the 3 times every 2 weeks for each muscle group per ABA BAB. And then in 2012, out of necessity, I started ratcheting down the volume and even toyed with reduced frequency from time to time. Presently, I am doing less volume than I have ever done. But I no longer anticipate my next workout with dread. I'm nowhere near the size I was at my peak, but then, I'm in my early 60s now. Long story short, it seems I spent way too much of my life at my personal ceiling level of volume, seeing how much I could tolerate. But was it necessary before it became impossible to sustain? Looking back, that was not a good way to spend life. I wish I had sought the minimum amount necessary to get a satisfactory, or even optimal, response, as Arthur Jones had urged. I so wish I had experimented with the kind of volume I'm working with now, when I was younger, to see what I could have achieved with properly performed abbreviated workouts in my prime. It saddens me thinking about the missed opportunity. Reading mainstream BB forums, I see that history repeats itself, with people fixated on how much exercise they can tolerate. I think Thibaudeau is perpetuating that idea, however much he may be trying to moderate or mitigate it with his comparison between naturals and enhanced.