Hi LasVegasFitGirl,
I'm currently on my 11th week of doing the STS/LIS rotation and I've supplemented the Hip Thrusts and Flat Bench Tricep Challenges into the days when I have legs and triceps.
I also did the Rock Bottom Rotation where I added the Hip Thrusts one week and the next week I did the STS squat rack, alternating each week.
I wanted to work more in these areas and it has really helped define my glutes and legs as well as triceps. I would have to say these areas are my weakest links and I've noticed a definite improvement in appearance and endurance.
These challenges also do not take long - it can be done in/or less than 20 minutes which is a bonus to add to your current routine.
GO FOR IT - you're going to like the results!
Monika