Shit, only thing that keeps me in the gym for <30 minutes is --- well nothinng. I don't think I do 15 sets of anything in a month. Used to do that shit when I was like 20 & stupid
All of my sets were with 1 arm, so it would have been 7 or 8 sets. I only work each bodypart once per week and I do as many sets as I feel like doing. Works for me. Most people criticizing my workout style, look like crap compared to me. (Not you though)