On the other hand, if you were ready for something different by week 2, then it may be that your personality does not suit remaining rigidly within a prescheduled list of exercises and routines. The very idea of imposing a routine upon my execise time sends me into overdrive rebelliousness.
Rotations can be excellent as previous poster suggests for tracking progress. But if you find them stultifying, there's a risk that by forcing yourself to do what's written down on the paper rather than what your body/spirit/mind most yearns or needs to do right now (say KPC or Cardio Kicks after an infuriating meeting with the boss, with his ugly mug as the punching bag!!!), you might pass on the workout altogether.
You should feel free to do exactly what you want to do, regardless of what anyone else is doing. However, if attempting something like the Slow and Heavy series, you will make this series more effective for you by sticking with it for the three weeks Cathe suggests, then it can really make a change in your muscle strength.
Rather than strict rotations, I like to go through phases, and they can last as long as my desire and inclination last and no more: phases of endurance for weight training and phases of focus on strength in weight training. But within those phases, I feel free to do any combo I like that tackles that focus. I would never do PH three times per week, rather, I'd do PH once, then ME another time, CTX upper body and LL once each. Then the week after that I might go back to the PS series....
Some people just crave variety, perhaps to counteract over rigid schedules in other parts of our working lives. Maybe you are one of them? If you are, feel free to be yourself!
If you stick with your workouts because you are following your heart's desire, with a nice mix up of both cardio and strength and stretching, you are going to see fitness gains and an improved outlook on life, no matter what the scale and tape measure say. If you are expending more energy than you take in, how can you not win?
Clare
