I can't speak for Cathe, but I have always read and heard that you should put a rest day or a non-strength training day before you do a circuit workout. I think even doing Power Circuit or Leaner Legs the day before would be too much, and especially any upper body weight training would be.
Try just doing a longer than usual cardio day the day before, maybe longer than the CTX cardio but not as high intensity. Then you add some good muscle confusion into the mix too.
I myself have a new rotation starting this Monday after doing the 6 day a week CTX rotation for 4 weeks. My new rotation will be (just to give you food for thought):
Mon- MIS
Tues- Powermax
Wed- Interval Max
Thurs- MIS
Fri- MIC
Sat- Circuit Max
That way I have all completely new workouts for my body to react to and I'm training each body part 2 times per week for stregth, I'm getting some upper body endurance training once, interval training once and some cardio that is completely different from what I got used to with CTX.
Does that answer your question at all? I hope it helps, at least. Again, I don't know what Cathe would tell you, but you do want to give your muscles adequate recovery time, otherswise the workouts become counter-productive. But I know the feeling, it's like you enjoy them all and want to do them all but you can't all at once. Believe me, I know!
Take care