I was watching a vlog from a girl who worked in housekeeping in the college program. At least some of her rooms, maybe all, were DVC/villas. They would just get a list of their rooms for the day and who was checking out. Sometimes, it would say when people were checking out but sometimes not. They started early in the morning, so they needed to be able to start on some rooms early. All of the rooms had to be finished before they could leave for the day. They would often knock on doors if they had no check out time info and there was no Do Not Disturb sign. Plus, DVC rooms can take a long time to clean if the kitchen/kitchenette is really dirty.
I guess just always put out the Do Not Disturb sign. We pretty much put the sign up the minute we get into the room and don't remove it until we leave the room, just in case.