re: 100 rep sets

Changing up a routine every once in a while is a good thing from my experience. It tends to give your muscles a "shock", which is good. Doing the same routine every week, while for some, may get tedious, it also allows your muscles to get "comfortable".

This is why I always try to do my lifts in a different order each week, and also switch up weight/reps. Some weeks I'll do lower weight, higher reps, other weeks I'll do more weight, less reps. Some weeks I'll do four days of full body workouts instead of targeting a specific muscle group each day.

Keep your body guessing, and you will continue to progress.