Kelly may not have hit the same area on back to back days because he presented a new concept with each episode. He wasn’t treating a problem area for a person. You may hit some places on back to back days sometimes you may not.
If it is a problem area you may want to hit it everyday.
You may hit something back to back days based on the elements within the workout.
If you feel you need a day off from working on an area work on something else.