I did Insanity too but felt it was too much cardio and don't see myself keeping that kind of cardio routine up weekly. I wanted to build some muscle, lose some body fat at a no-so intense rate. P90x does that. I don't everything in the videos. Plus I don't want to bulk up, I just want to strengthen my abs, shoulder, legs, and back as well as become quicker.
I'll admit. Sundays are usually my off day, and Wednesday may involve tennis vs. working shoulders and arms.
Tony's run around the towel routine, I substitute for that skipping,cross-step, twist thing the pros do. It is simply cross-training for me. Those periodic back or shoulder problems are gone (fingers crossed)