MIS & PH are endurance workouts, and S&H is a strength and mass building series. Cathe designed the S&H series to for each tape to be done only once per week (as is the PS series), and to be done for only 3 weeks at a time.
The PS series was meant to be done for longer rotations.
If you had the S&H series, you could do MIS & PH for 3 weeks, then switch to S&H and do it for 3 weeks. Very simple, very easy.