Years ago when they got rid of DO's it was leaked here and in other platforms that they were planning to make all CO's part time as the now subCO's are. Local, well connected, and very loyal elders would be used to do the visits and oversight of circuits. The goal was to distance the Org from directly seeming to control the congregations. However, it did not get fully implemented although it was tried out in some places, like in New England, for a brief time where some congregations in NE only had subCO's for a few visits.
It was decided not to go with the plan, probably because the scene was changing and it was becoming legally helpful to keep a Roman Catholic hierarchical structure in place.