Almost every hotel asks guests to leave in the late morning and arrive in the mid afternoon. The interval between the two is not a convention but an operational requirement created by housekeeping.
Every departed room must be serviced in one window
A room that has been vacated needs stripping, cleaning, restocking and inspecting before it can be reissued, and that work cannot begin until the guest has left.
A full property therefore generates a large number of rooms all requiring the same work within the same few hours, with no way to spread it across the day.
The gap between the two times is simply the duration required to complete that work at a realistic pace, given the number of staff on shift.
Staffing is sized to the peak, not the average
Housekeeping is scheduled against expected departures, and a hotel cannot economically employ enough staff to service every room in an hour.
Rooms are assigned in quotas, with each attendant responsible for a set number, and the last room in a quota is finished several hours after the first.
This is why arriving early sometimes succeeds and sometimes does not. It depends on whether any room in the arriving guest's category has cleared inspection.
Laundry sets a rhythm of its own
Linen stripped in the morning has to be washed, dried, pressed and returned before it can be used again, and that cycle takes hours.
Properties hold enough stock to cover a set number of turns, but the buffer is finite, and a high-occupancy night followed by a full arrival day tests it directly.
Where laundry is sent off site, the schedule is fixed by collection and delivery times, which removes any ability to accelerate on a busy day.
Maintenance and inspection sit in the same window
Faults are discovered when a room is cleaned rather than while it is occupied, and a room with a problem cannot be released until it has been attended to.
Supervisors inspect completed rooms before they are returned to the available inventory, which adds a step between the work finishing and the room being sellable.
Deep cleaning and preventive work are scheduled into the same daytime window, so a room held back for either is unavailable regardless of demand.
Flexibility is sold rather than given
Early arrival and late departure are offered as paid options because each one removes a room from the turnover cycle for part of a day.
Loyalty programs often include them as benefits, which is a way of allocating a genuinely scarce resource to guests the property most wants to retain.
Luggage storage exists as the compromise, letting guests separate from their bags without the property having to release a room outside the cycle.