I'm not a one gun guy but I'm about as close as you can get.
My "carry rotation" consists of a Glock 19 and a Glock 26 and I "rotate" based on my concealment needs. I have a Glock 43 for deep concealment but I think it's been 5 years since I've actually had a need for that level of concealment.
Having different guns for different purposes isn't really the same as having a "carry rotation".
Having a "rotation" usually carries the connotation that you're switching guns because you're bored with the one you've been carrying