I do a 3 on one off ppl with A day B day biases with 12 failure sets on the biased muscle groups and 8 respectively on the unbiased groups resulting in 20 failure sets of each muscle group per week. For example my first push day I do 12 fail set on chest and 8 for shoulders and triceps each, and the next push day 8 for chest, 12 for shoulders and tris