I say 3-4 days, but I can't count the times that I'm sick. In fact, I use that as a barometer of how sick I am. If you lose your sexual appetite...you really are sick! I didn't even try for an orgasm for almost two weeks once because I had mono. A sad, sad time.
But in good health, three days is a struggle.
Some days, though, three hours is a struggle.
I've been told I have a man's libido. Hmm...