Love your playing (and your take with this thread)!
I have been training two days a week, HIT-based full body routines, for the past 1,5 years. Works wonders for me, as my strength and weight gain has gone uphill - until fairly recently. Most likely severe stressors in life at play - or adaptation, why I shifted from Dr Darden variations to Brian Johnston’s Zone Training approach (now more a mix of volume and intensity, yet to be evaluated).
The key element with only two days a week is to maintain high intensity, obviously. By doing so, you need the prolonged rest periods. I do 2 sets for bigger muscle groups, and 1 set for the others - to failure, or on a bad day, close to failure. It’s easier to motivate myself to perform, when only one set counts. Oh, and I tend to prioritize different muscle groups every workout (changing order, prioritized first and maybe adding an excercise on that particular muscle).
When I previously did high volume body splits, five days a week, I just followed a simple protocol. Nowadays, I spend significant time planning my workouts, to make the most out of them - in order to keep the element of surprise against adaptation. It’s actually quite rewarding to plan next days workout: Hm… On triceps - Should I do negative only, slow or fast cadence, high rep or low rep? full rep or zone training? What kind of excercise? Free weights or machine? What did I do previously? What felt good? What produced results? Room for improvisation/freeform?
This may seem like an obvious approach - but since were talking about just one set - it’s more important than ever. Previously, while doing 12 sets/3 excercises on a muscle group, for example, I never focused on detail. It just wasn’t that important. Why doing more sets when 1-2 is enough?
As @fitafter40 said you get more time for other activities with this approach (family time in my case). Though, I tend to think and read more about excercise these days, as stated above. Apart from work and family activities I play the drums, which is my only other “excercise”.
Shit, this became a long rambling. Sorry for that!