I have found that the maximum number of sets that should be performed for the best pump is 12. Anything above this is over-work and causes the muscles to contract and lose their blood supply. I have seen this happen to top physique stars; it has happened to me.
Remember, maximum pump involving the same muscle(s) in every workout does not build tissue.
Because it takes 72 hours to rebuild muscle tissue after this sort of work. In other words, take care to rest adequately between workouts, to permit muscle repair and growth.