The intensity of a weight training workout is different according with the number of sets, reps, weight, and intervals of rest. Modifying one factor changes the others. Lifters can do more sets and reps if they utilize lighter weights. As a result, short rest intervals prevent recuperation and decrease the ability to lift more weight and perform more sets and reps.
Studies found that athletes accomplished greater training volumes when they had a rest of three minutes between sets rather than one minute during an upper body workout involving three sets of five exercises at a weight equal to a maximum of 8 reps. Training volume is just one measure of the efficiency of a workout. Short rest periods sometimes cause larger increases in anabolic hormones, which might generate greater training gains.
Longer rest intervals, like five minutes might be more suitable when doing heavy singles or doubles. The effectiveness of programs can be judged by gains in muscle mass and strength and not just by training amount of individual workouts.