Ok, the reason i said lifting 100 5 times is better than 20 25 times is because of the effects each has on the body.
When you lift a weight for a 5 rep max, you will stimulate IIA and IIB muscle fibers - these fibers have the largest diameter and the highest potential for growth. With a 5RM the Type I fibers will not be needed at all, because the TUT is not long enough for them to be recruited, as they are only used in endurance activities. So the 5 rep set will stimulate Type II fibers to the exclusion of the Type I's, while a 25 rep set will stimulate Type I fibers to the exclusion of Type II's. If strength and size are your goal, you should be focused on the IIB's.
FYI, Type I = Slow twitch
Type II = Fast twitch.
Of course there is much more to it than that, but it's not really necessary to get into it here.
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Complex problems have simple, easy to understand, wrong answers.