I think there's two things missing here. One is that not everyone leaves on the same day, so cleaning would still be distributed throughout the week. Secondly.

I think there's two things missing here. One is that not everyone leaves on the same day, so cleaning would still be distributed throughout the week. Secondly. They could still require something like once every 3 days. My room is always spotless when I stay, I don't understand how cleaning it for most people would take much longer.