alt Hacker NewsTime under tension is an imperfect measure, it's just less bad than other measures we could use. Sort of like lines of code in software engineering. Given that, saying it's "just TUT" is misleading.
It could turn out to be that the brain is coordinating hypertrophic biochemical cascades in muscles, and TUT is just a fairly reliable method for inducing this.
I was a competitive powerlifter and trained around pro bodybuilders for years, and in my experience, the only commonality between them was the intense all consuming drive to be absolutely monstrous (and they ate a lot). Some would train for 2 hours a day, some would train for 45 minutes 3x a week, some would use high volume in the 50-70% range and others would focus on 70-85%, some were explosive some were slow and steady, really it was all over the map.
Well... I didn't say "time under tension". I said tension x time under tension. It's the integral. So high volume 50-70% can equate out to medium volume 70-85% for hypertrophy, all other factors being equal.
I'd guess that drugs come into the equation if you were training around pro bodybuilders and that unlevels the playing field between each person because of how much they might have been on. And amongst the pro's, you're going to hit those genetic Mentzer-like freaks that can somehow grow on 45min 3x a week.
100% agree that drive and intensity is key, and there is more than one way to get big from a program POV.