Scientific research published in 2021 from a group at the University of Cambridge showed 70 percent of one repetition maximum worked best for building muscle. You can try that if you like or bump all exercises up to 80% of 1-RM on all exercises following a few warm-up sets. Study author Eugene Terentjev said that their mathematical model suggests that loads of 70% are a more efficient method for muscle growth because too low a load will not activate titin enough, while too high a load will cause exhaustion to the muscles. The idea behind this routine is to use approximately 80% of the most weight you can handle for each of the 21 different exercises in the routine. For example, if 225-pounds is the most weight you can handle on a bench press, for one repetition, then you would use about 180-pounds for your sets following your warmed-up set(s). Stray Strong Together, MICHAEL WOOD, CSCS Jefit