
This feature was designed with larger hotels in mind. In full-service hotels, for example, it is the best way for housekeeping to communicate with the front desk on rooms and statuses.
Throughout the day a housekeeping supervisor would update rooms as they are cleaned. They make note of whether the room looks occupied or vacant and enter their status based on what's in the room. This will create discrepancies.
For example, a room that is vacant in Front Office but housekeeping says is occupied tells the front desk they need to find out who is staying in this room. Maybe the guest got checked out by accident or a room move happened but the reservation was not moved in the system.
The other discrepancy is more commonly associated with express checkouts. The room is due out but not checked out, housekeeper cleans the room and reports the room is vacant.
Probably around check-out time is when the front desk would want to run a discrepancy report and take care of the rooms on the list.