I tried to do each STS disk twice per week and found it was too much. I only did it for a few weeks - definitely couldn't maintain it for 3 months. Forearms were sore from holding those heavy weights 6 days per week, and it just became too much work and not enough FUN. Also, deadlifts pop up in both the upper and lower body programs so doing it twice per week meant way too many deadlifts. I decided to do it once per week as designed and then I felt fresh for each workout and there was no dread factor.
Doing a total body workout once per week may be a good option for you Amy30. I often planned on doing that but never ended up carrying through.
But, STS gave me good results as is, and so I personally found the extra weight day wasn't needed. I sometimes did metabolic workouts or circuit training (e.g. Drill Max) on my cardio day and so used light weights then.
For me, time-wise, fitting in 3 STS workouts, 3 cardio workouts, 2-3 core workouts and lots of stretching (needed after STS!) was a challenge and all I could squeeze into a week. (Plus, I am still really slow at getting my weights and barbell all set up before each STS workout - but that's just me!) And that doesn't even include time for planning and prepping healthy meals and snacks (I just can't seem to do that quickly either!
) If I did have extra time, I did outdoor activities like biking, hiking and cross-country skiing.
Let us know what you choose and how it goes! Good luck Amy30!!