Fromt-end loading ?'s

[BTLFED]

I read a post about two weeks ago on front end loading with Sos, and another yesterday on front end loading. From what I understand it only makes sense to front end load anything that has propinate as a part of the mixture, Ex. Sos, Ara, T-400. My question is, why do most magazines that refer to As cycles, instruct people to inject twice a week with Sos, and what is the point of even putting prop. in these products if it is wasted, sorry if this is a stupid question, but the threads got me thinking.