The easiest route to the PT Patch requires only knowledge and intensity. Mistrust anything you read that talks about plans, numbers, systems and tables, yet doesn't explain in exercise physiology terms why their plan is the solution. Understand how your body works, then develop your own plan. The keys to success. Specificity and Intensity.
Exercise is very specific.
That means that if your event is the APFT sit-up, then that is the exact exercise that you need to train on. Crunches, leg lifts, etc. are fine, but they are the icing on the cake, not the meat and potatoes. When you are doing sit-ups, to use an example, with your feet anchored and doing repetitions at approx. Not a simple issue. Specificity means that you get better at the exact exercise that you train on, which only makes sense.