I carry a Glock 17 Gen 4 as an EDC, but will carry my 9mm Walther PPS when the Glock is too cumbersome for my given task (PT, running, etc). Defensive ammunition used in both firearms is identical, and reliability has been vetted. That's my carry rotation.
I've been fielding questions from folks back home about carry, and the topic of a "rotation" has come up. I've directed them to take a class with John Murphy and spend their training money on practice ammunition instead of getting a Taurus Judge or Canik.