After reading the reports here, I actually wondered about this on our trip last week, as we were in the room till 10am, and my brother was in his room till 10:50. Neither of us got a phone call or knock, although the basket of new sheets and towels was in front of the room from about 8am on...they left us alone completely, despite the lack of "Do Not Disturb" signs on both doors. My brother had arranged for bell services at 11am, so perhaps they had noted that, but we had a rental car and did not give any indication as to when we were leaving.