If you consider doing 20 sets, than give it a try and than learn by that experience. If you make gains or perhaps lose a little muscle size in the process can only be determined by the results you get. Might want to do the one body part a workout theme though. Set aside a 6-8 week period to have a true test run on high set's. We all have to give just about any workout system a true try to see if it's for us. Reading about some of those 60's-70's BB'ers who do 20 set's plus, three time a week is amazing. Dave Drapper comes to mind. They did use a lot of SS's, Tri set's, Giant set's, etc. The 'roids use was not that extreme in those day's, I've been told. As mentioned before, a very popular method was 15 sets a muscle group a day on the lower level of the extreme.
Of course in the real world of training (for most normal guy's), if you can't train a muscle group to respond and become larger and stronger, progressing each workout, with between 4 to 9 sets max than you may want to see what your doing wrong. Of course this is all without going to the state of failure at any time during a workout. And as we all know, using gear does not always give magical results for everyone. That word again, genetic's has a lot to do with how each one of us responds to a shot in the butt of that joy juice. Good Luck.