Question: should i do reps to failure?
Answer: On Level 3 exercises, I recommend avoiding failure in training. ... So, when training for strength you should stop these exercises 1-2 reps short of failure. When training for size, stop 1-2 reps short on all but the last set, on which you go to failure. For Levels 6 and 7, I recommend going to failure on all of your sets.