I do full body workouts 4x a week, in a push/pull split, and do alright (and I’m 30, I need my rest :p). I think the poster’s pushup/pullup business on the interval days isn’t going to make a lot of difference, and would be better served with weighted chins and pullups during the regular sessions (swapped in instead of the bicep isolation work.)
100 pullups in a session would be quite impressive… I might go for 25 or less… if that’s easy for you do weighted ones. And 100 pushups might be a little unecessary, might be better served by doing some plyometric work or speed strength work if you’re an athlete.
The program you’re talking about is a canned program…BUT, it was released by a well-respected author, presumably tested over a range of trainees, and has met with very favorable reviews since its release.
You are sixteen…any modifications you make to the routine, particularly with regard to the periodization scheme as you have done, will only make the program less effective. The original template Waterbury provided allows for considerable freedom with regard to exercise selection. Just do exactly what he says with the sets, reps, and rest intervals.
Are you restricted by working out at school or during the week? I think you’d be better off doing weights, energy, rest.
You’d get 4 workouts every 6 days instead of 5 every 7, and each time you’re coming back to weights fresh. After 5 weeks you’d have 24 workouts instead of 25.