Two times, one schedule
The mistake is to treat late nights as an exception managed informally between the office and the regular cleaner. A schedule with one nominated time and a general understanding that it moves on Thursdays will be misapplied the first time somebody else covers the run, and the office will find a cleaner arriving in the middle of trading. Writing both times explicitly into the document removes that ambiguity entirely.
The second time should be derived from when the back-of-house area actually clears rather than from the published closing time on the door. Staff typically remain for a considerable period after the doors close, completing reconciliation, restocking and handover to the following day. The office is usually the last part of the premises to empty, which is exactly the area the schedule is aimed at servicing.
