I always have a NAA mini revolver (single action) because, I mean, why not? It is no more trouble to carry than a pocket knife. I have it in a "hoster grip" for shootability and it's amazingly accurate and a fun plinker, though of course will never win a bullseye shoot. I've used it for a lot of critters, snakes, a few rabbits, couple of coons and possums, a wild feral dog once. It backs up whatever serious self defense gun I might be carrying. I figure, if I'm carrying my .38 and behind a barracade and making a reload and the BG starts charging me, it might be faster just to grab the NAA and pop him a couple. Anyway, it's always there because it's so bloomin' easy to carry. You just never know what might happen and it beats tooth and claw in a pinch. Makes a pretty loud bang with that short barrel, too, which is a good thing. Maybe the BG will think it's a .38 and run if that's what I have to use. I ain't countin' on that, though.
Only time I carry my other single actions, Ruger Blackhawks, is open carry while hiking or hunting or something.