Each female really only needs to be with him once a month, although I know people like to do it more often. Be sure to give the male nice breaks between females, to allow him to eat and rest. At least 4-5 days when you plan to feed him - allow him to digest his food.

I do 3 days with a female, 4 days rest as a cycle. If he hasn't locked with a female in the 3 days, he's not going to during that rotation, so there's no need to keep him in any longer.