Mike Mentzer was an incredible bodybuilder in Arnold's time period, and a personal trainer after retirement, most famously couching Dorian Yates He was very smart and scientific in his approaches, and came to the conclusion that exercises should be done to failure. This meant that his program required significant rest time, and he did very few sets per muscle Simply cycle through the 4 days, adding cardio or other activities as appropriate. Take as many rest days as necessary between. This means paying attention to your nervous system. We want to attack each workout with maximum effectiveness. If you don't feel like your nervous system is at least 90%, take another rest day. You might end up 1, 2, 3, or more days between workouts, and there is no shame in that. It is for long term benefit I'm trying out this first version myself. Any feedback, questions, or recommendations for the future are appreciated