What most people fail to realize is that HIT, jones style incorporated negative work, something he didn't invent a method used by bob peoples a negative only style training, this was in the early fifties.
jonse took it a step further, through testing, he discovered, the reason one can lower heavier weight is - internal muscle friction.
if you positive strength is 100
the negative strength will be 40% higher, static strength will be 120%.
exhausting the muscle in this manner is true fatigue, the results he achieved were phenomenal (West Point study)
and PTC, project total conditioning.
measurements were taken, growth occurred overnight, and in some cases, during the workout.
Intensity of work is subjective, in that the threshold of pain differs for everyone, the degree of inroad one takes on an exercise will differ from one person to another, what we do know is results are tangible.
one telling another that he or she does not work to full fatigue is an idiot, in fact one only works to fatigue when one has exhausted 100% of fresh muscle strength and needs to be carried from one machine to the next, this is what happened at Deland Florida on a regular basis.
Arnold tried, quit after 10 minutes, later denied he ever went there, although there are pictures of him on the machines lol.