Haven't tried it yet, but I expect that you can use the scheduling menu to set up what you describe once, and switch them onto that schedule as needed. You'd want to set up a schedule with multiple station commands, each with a dwarf count of 1, on each tile you want them to stand.
Then you can swap them with a couple clicks between training, off duty, and whatever station schedules you need.
Then you can swap them with a couple clicks between training, off duty, and whatever station schedules you need.