Not enough, i often rely if my partner is in the mood or not.
We only had sex once this month :( we dont live together so the opportunities are slim but my sex drive is waaaaay way way higher than his.
I think you should have as much as you want, as long as it doesn't become an addiction. Sex addiction is harmful, look at fouseytube or whatever his name is.
Though i want to fuck at least once-twice a weekday, weekends can be a break, at most i want... Twice everyday, maybe a max of 8 times. Depends on how long or short the sessions are.
Oh, and healthy? Yeah, sure, if youre not acesexual. Being sexually repressed / frustrated is NOT healthy, so sex is good if you want it!