Yes so I’ve been thinking about this myself a bit as well. I’ve been training PPL twice a week for over a year prior to getting into Joe’s program recently, because I believed in the literature saying working each body part twice a week is better than once a week. But when I train really hard (training to failure with heavy load like in Joe’s workouts) for each session I just can’t recover a body part(especially legs) in just 2-3 days. So what I did was split each body part into base work and pump/activation work where in the former I do all the meat and potato stuff and progressively overload and in the latter I just do some pump works and try different workouts or might do a couple of heavy load work if I feel good. I still follow this kind of routine just cuz I like to go to the gym everyday. But I guess from a hypertrophy pov, Joe prefers single sessions per week because the more advanced you are you won’t really grow unless you produce sufficent force which you can’t really do with those pump works and he would rather rest to recover fully and get the most out of the meat/potatoe workouts. This is just my thought on his approach and I’d love to hear from Joe on this question. But I think the most important thing is to really train to failure or very close to failure with the meat/potatoe workouts and progressively overload with perfect form with those and with good nutrition/rest you will grow.