I agree with a lot of what’s been said above. Intensity is a % of 1RM. Intensiveness is a RPE. The one all-out set style should have originally been championed “Highly Intensive Training” but whatever.
I personally always liked the old adage, “if you want to do more than one set, you’re not training hard enough.”
Only because I personally prefer to warm up and do one all-out set. Not because it’s the most effective way to train. No where near it. Its just what I enjoy.
Part of me wishes I had followed high volume BB-Stlye bro splits for at least a little while in my younger days to gain some size so that today, I could actually look as strong as I am.
Although, it is fun to walk in a gym looking like a 40 year old couch potato and blow peoples’ minds with big weights.
Training with either High intensity or high intensiveness will get you strong but not very big at all (genetic gods aside). Training with higher Volume and frequency will get you big, but not very strong.
Before you all flame me, let me illustrate my point.
Lifter A). One of the best bodybuilders out there who nearly everyone respects, John Meadows. Trained on high volume BB style bro splits forever, still does. Dude has 20-inch arms. I watched one of his videos the other day and he was doing rack pulls from just below the knee with 405. It was heavy for him. His rep speed slowed significantly after a few reps.
Lifter B) Me. Trained using one all-out set for my entire lifting career. If you saw me on the street, you wouldn’t even think I lift. I’m one missed training session away from looking like Barnie Fife. 405 in the rack pull is child’s play for me. I routinely rep 585 RDL style without using the rack pins
If you want to look like you lift, and you’re not a genetic god, you need volume.
Ideally, we should all train with a good mix of both.
Unless of course, you are someone like Mike Mentzer or Casey Viator and your muscle bellies are exactly the same length as your bones and you have triple the androgen receptors that other mere mortals do.
Then you can do one set of walking in the gym and taking a sip from the water fountain every 19 days and get yoked out of your mind.