>>76811644
Yates said that referring to failure per exercise. If you look at Blood and Guts he does multiple lifts per muscle with the amount of sets he's doing per muscle to failure being close to what I was recommending. Even his warm up sets were still taken to like 3-4RIR which is still a training stimulus if you watch him train. Both in the gym practically and in labs measuring people it's been landed on that about 4 failure sets in a session will give you the maximum stimulus for growth with everything below that still working but not to the same degree and far above that doing more harm than good most of the time. For stubborn body parts maybe 1 or 2 more failure sets would be beneficial but that's about it
>>76811648
I'm talking about optimal volume for growth. You'll still grow on less but maximum growth needs more volume than Heavy Duty recommends. If you do 1 set to failure you'll eventually hit a wall and you can get around it by adding rest-pause sets and dropsets to keep the set going for similar results if you for sure want to only keep doing 1 true set per lift but you would be better off just adding another lift targeting the muscle and taking that to failure too. Something that targets the muscle from a different angle or has a different strength curve would be best