thank you for the suggestion..
Quality of semen depends on your general health. It takes half an hour between two intercourses normally. Doing more number of rounds does not mean good quality of sex.The more rounds you do less you enjoy.Quality means good fore play,Time enough to satisfy the partner, Orgasm at the same time....If on does more round, he misses atleast in some aspects.
In over zeal, you do much more round tan what is good for you and then you lose your usual momentum.