I wasn't thinking in terms of WW2 but as a methodology in the later stages of the Union such as in the 1980's.
From what I understand, if in a WW3 situation, the Soviets divisions would advance and in high intensity conflict sustain massive casualties for only a few days. Then, they would replaced in the front lines by a fresh divsion and repeated until either it won, stalemate or lost.
Another thing to remember was the category A divisions wouldn't have a full personnel strength but would have a full equipment strength and which would require some time to assemble personnel. Thus alerting NATO of a planned attack. Of course it could attack at a moments notice but it wouldn't be fully manned. They were to be only fully manned if a general mobilization was ordered, altering NATO.
EDIT
Sorry, I didn't explain that used up divisions that attacked when used up would be sent to the rear. But wouldn't be reinforced with new personnel. It's highly likely that nukes would be flying at this point rendering the whole world dead and nothing to fight over.