It is the nature of refurbs that
DVC cannot usually just do something like the GV's or the studios separately. Renovating the rooms along any hallway results in a lot of workers using the hallway and throughout the day transporting work equipment and items to be added in the rooms and removing things to be taken from the rooms. They thus need to close off the applicable hallway to regular quests, with the result that the usual process is to do rooms that are along the same hallway at the same time, including those on both sides of the hallway.
The only exceptions that exist at WDW where they could do just one size of rooms at one time are the studios in the new VGF building (since all are studios), the Poly bungalows, and the CCV cabins.