Frequency is a tricky subject
I think waterbury has good ideas but its rough around the edges. Can his program work good? yes
could it suck? yes
you need to have good recovery levels, fitness levels, and do some instinctive training on nowing where to draw the line with how hard u train.
one thing I have noticed alot is kids who are very strong for High school athletes usually train things 2 or 3 times a week. when they switch to bodybuilding routines trainig 1x per week, they usually notice an imediate loss in peformance. My brother is 18 and benches roughly 400 lbs. he will not gain benching 1x per week.
The thing about frequency is if your training single factor theory everyones personal frequency might be different based on recovery. one person may need to rest 5 days after a certain workout where as athlete B's level of preparedness will have already declined after 5 days. (he waited to long). so its a lil trial and error. an athlets level of preparedness is always changing and differenent athletes will change at different rates.
alot of other countries follow Dual Factor theory Training. You don't need to be fully recovered to train again. One thing that Waterbury doens't mention as his methods are completey Single factor theory with fatigue management built in. I also agree that Gymnasts are pretty muscular without lifting wieghts. but i would thinkg their training more resemblest DFT training.
they don't progressively load their muscles everyday.
lets say they do a very intense workout on Monday and Tuesday.then a light workout wedesay and take thursday off.
so Monday and Tuesday would be the Fatigue days....and wednesday and thursday are the recovery days.
most gymnast, lumberjacts, olympic weight lifters don't usually follow the single factor method. IE TRAIN---Recover/Grow-----TRAIN (add more weight)
they follow the Fitness Fatigue theory.....where multiple workouts would represent a fatigue period followed by an uloading period.
So i think some people could over train quickly on Waterburies programs b/c of the Fact that "fatigue can be cumulative".
So i think increased freqency can be good. but something may work briefly and then quickly overtraing b/c of the fact that fatigue can be cumulative. so frequency can defintely both Make you or Break you.