Perhaps I've misunderstood something, but from what I've gathered, there are no longer any DND signs at WDW, and even if you have a "Room Occupied" sign on the door and mousekeeping, for example, made up your bed yesterday, much less than 24 hours ago, security will still knock on your door. Even if you're taking a nap in the afternoon and mousekeeping serviced your room that morning. That is a big difference from having a DND up for 24+ hours and no one has had any access to your room except you.
When I'm in a hotel and I put the DND up, it's because I don't want to be disturbed. At all!