I tend to leave my bucks with the does for 10 minutes while I'm cleaning or doing odd jobs, and have had them cover the doe sucessfully around 4 times in those 10 minutes - naturally depending on the doe being receptive! I do know other breeders that will cover 2-3 does with one buck in a day, but as long as they're experienced and don't mis-fire too much, they could probably manage more.