mykeal is correct.
I swab between every shot. In the field, I keep a plastic Skoal can in my pocket (to keep it warm) full of either T/C pre-soaked patches, or I pre-make my own using Simple Green.
After a shot, I run 2 or 3 wet patches (I roll them into a ball between my fingers so they're not too wet, don't want to foul the nipple/breach plug) until they come out fairly clean. Run a couple dry patches. Load powder and sabot, ball, etc. After loading, I run a patch of Ballistol to protect the barrel and keep it from freezing. I can do this in under 2 minutes and well worth it!
Black Powder: Not because it is easy, but because it is hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win...