I just finished a project where I made up to ten carves (each one was different, but that doesn’t matter) from a single 48x24 plywood board, putting each carve in a separate workspace. Then I went through and carved all the rough cuts first, one by one, then changed bits and did each of the finish passes. Since I zeroed the router to the corner of the workpiece board, I didn’t have to rezero the X/Y every time.
The only thing that would make it simpler would be if you could import more than one STL into a single workspace.