I changed my time from three minutes between sets to 30 seconds. I am doing 4 sets now but i notice that my wieghts dont' increase for each set cuz no rest. My goals are to add mass so I was wondering if i alternated each week for example go one week with the rest between sets for like 3 minutes to get the wieghts up higher or doesn't it matter as long as the muscle get stimulated properly?