I had the same question about single pairings so I asked Adam in a PM. Here is his response (I am sure he won't mind me posting it)

When I do one to one pairings I still do the same 2 day cycles in and out of the females tub ... seems like after a couple of days the pair gets "stale" and taking the male out for a little bit and resting him and then putting him back in livens things up again. Also, with one to one pairings something I just do 3 on, 4 off with the pair ... it's nice because it's a lot easier on the male than running him through a bunch of girls and having him do all that work.

Hope this helps

-adam