Just curious, did you read the linked article I posted earlier? I'm guessing you didn't. In any event, if the exercises, at least the same ones of different weight, were not taken to failure, then what was the cutoff point for stopping the exercises, and why? And if they were taken to failure, then why would he not have said so? Perhaps you are more confident in the findings than you ought to be.
I think it's very difficult to quantify the "best" exercise across many subjects. A MAJOR key is the mind muscle connection. I remember seeing tons of people seemingly do the exercises correctly yet they had no growth or strength increase. I attribute much of that to not feeling the movement.
I agree that just going through the motions of banging out reps is not as useful as making the reps as hard as possible and really feeling the muscles worked. For me it's about the focus. When I'm doing a set, and especially as I approach failure, nothing else exists. I suppose you could say it has a meditative quality. Perhaps that's why I find working out to be therapeutic, along with the release.