When you make the decision to embark on a training program whether it's a Vertical Jump System or any other workout programs, you need to plan out to the future. If you start right in from the start and go all out then a few weeks later you quit because your dissatisfied in the results, hurt or worn out, your energy and time has been spent for nothing. Then what happens is weeks or months later you dive right back into it again with the same conclusion.
If you are a trained athlete you can most likely get away with going all out, but if you are just beginning to get into shape take it easy at first and ease into it. Think long term, set goals further into the future for what you expect your results to be and you are more likely to complete those goals. If you are drained one day or need to pass up a workout do not agonize over it, it may actually be good for you because your giving yourself a day of rest and your body can recuperate.
If you are just starting a vertical jump program don't try to reach your objective as fast as possible, take advantage of time to build yourself up to be successful. If your legs are not strong enough yet spend the time to do the squats and dead lifts you need to do, but do not cut corners to try to hurry the process. When you begin the explosive strength development do not overdo the plyometrics because you are only going to multiply the danger of injury and burn out.
Also, when you take on a particular program stay with it to completion to get the full benefit. If you bounce from program to program you will never see the best results you may be able to achieve. And take care of yourself, take some time off to allow your body to regenerate and you will actually realize you make better progress.