According to TripAdvisor, 31 percent of people don't tip hotel maids at all, The same maid may not service your room every night of your stay.
Depending on the hotel, maids may be assigned a list of rooms to clean or choose. way, some menu items just don't lend themselves to record service times.
General question do you expect your hotel room to be cleaned while you're in it?. I have a DND out and they call on the phone to ask if I want maid service.