Since he figures out how much weight he can do 12 times, is that how much weight he uses in set 1 and decreases weight each set? (popworkouts.com)
The amount of weight you use for each of these exercise should be approximately 60 % of your one rep max, unless the exercise specifically recommends otherwise. (build-muscle-and-burn-fat.com)
Lately I've been trying to decrease the amount of weight I use, but I can't stop going because its mandatory. (rachaelattard.com)