In my opinion PF tek is the opposite of the way cubes grow. What a decent harvest is varies, but it is likely impossible to get a decent harvest from such a method and those who grow that way subject themselves to inordinent amount of work for very little payoff and not much of an education on how the organisms actually grow.
I know PF guys defend their methods but the method was, from the start, a way for one many to make millions while making others dependent upon his system.
If one needs to rehydrate one's entire substrate, then they have not achieved the 80 percent point - that is the first three flushes yielding 80 percent of the total yield. The longer one is forced to keep a grow working past that mark the more likely that person is to contamination and difficulty with the environment.
Among all the methods of growing this organism, PF is the very worst.