Your comments

I get I can deny it. When all muscles are feeling good and I don't know how many challenges the app is going to present to me in a workout and I don't know which muscle group would benefit the most by doing the challenge then I can't make a good decision on whether or not to do them.

I had one for almost every lift in the workout. So one for bench, one for biceps, one for triceps, one for rows, and so on. All in the same workout. Seems like a lot all at once, I think 2 challenges in a workout is doable. More than that and the others I don't think I perform as well as I could on.