Housekeeping on a hotel floor is a routed operation, not a set of independent visits. The order in which rooms are cleaned is planned, and it determines when any particular room becomes available.
The cart anchors the route
A fully stocked cart holds linen, terry, amenities and supplies for a full section, and it is heavy enough that moving it is a considered act.
Attendants work outward from where the cart is parked, cleaning adjacent rooms before repositioning, because every extra trip down the corridor is unpaid distance.
Restocking happens at a floor closet or from a service elevator run, and those trips are batched rather than made whenever an item runs out.
Checkouts and stayovers are different jobs
A departure room is a full clean: strip, remake, deep bathroom, reset every amenity and check the room against a list. A stayover is lighter and faster.
A floor typically carries a mix of both, and the sequence puts departures first because those rooms are needed for the afternoon arrivals.
Stayovers get worked around the guests still in them, which is why service on an occupied room often lands in the middle of the day rather than early.
Priority requests reshape the order
A room needed for an early arrival, a VIP arrival or a guest waiting in the lobby is pushed to the front of the queue by a supervisor.
Every such interruption costs more than the room itself, since it usually means abandoning a route, moving the cart and returning later.
This is the real reason a front desk can rarely promise an exact time for an early check-in. The answer depends on where the attendant currently is.
Inspection is a separate step
In most full-service properties a supervisor inspects departure rooms before they are released back into sellable inventory.
The room is finished but not available until that check happens, which creates a lag between the attendant leaving and the system showing the room ready.
Where inspection is spot-checked rather than universal, rooms release faster but variation between rooms is wider.
The floor's rhythm follows the building's
The morning is dominated by stayover service and early departures, the middle of the day by the bulk of checkouts, and the afternoon by finishing and turndown preparation.
Deep cleaning, mattress rotation and carpet work are scheduled into low-occupancy periods, since those tasks take a room out of service for longer than a night.
Understanding that rhythm makes the practical requests obvious: ask for service early if you want the room done before you return, and hang the sign if you do not.