Almost every hotel sets check-in in the afternoon and checkout in the late morning. The gap exists because housekeeping capacity, not preference, determines when rooms become available.
Housekeeping is a throughput problem
A room takes a defined amount of time to clean thoroughly, and a housekeeper can complete only a certain number in a shift.
Multiply that by the number of departures and the hotel has a fixed volume of work that cannot begin until the previous guest leaves.
The window between checkout and check-in is simply the time required to process that volume with the staff available on the day.
Occupancy determines how tight the window is
At moderate occupancy some rooms were empty the previous night and are already clean, so early arrivals can often be accommodated without difficulty.
At full occupancy every arriving guest is waiting for a specific departing guest, and there is no slack anywhere in the sequence.
This is why the answer to an early check-in request varies so much between visits. The policy is unchanged, but the underlying capacity is not.
Staffing is scheduled days in advance
Housekeeping rotas are set well before arrival patterns are fully known, and staff cannot be added at short notice when departures cluster unexpectedly.
Many properties also use contracted teams paid per room, which introduces a further scheduling constraint on how quickly volume can be increased.
A hotel that appears half empty may therefore still be unable to release rooms early, because the shift was staffed for the forecast rather than the outcome.
Room types are not interchangeable
A guest holding a specific room category cannot simply be given whichever room is clean first, so the queue is really several parallel queues.
Connecting rooms, accessible rooms and suites exist in small numbers, and a guest waiting for one of these depends on a single specific departure.
Cleaning order is prioritised against arrival lists for this reason, which is why some guests are accommodated early while others with later bookings wait.
Late checkout costs the hotel twice
Granting a late departure removes a room from the cleaning sequence at the point when the team has the most work to complete.
It also delays the arriving guest for that room, which converts one accommodation into two inconveniences and a longer queue at the desk.
Hotels consequently guard late checkout more carefully than early check-in, and it is usually offered only where the following night's occupancy is known to be low.