Why a bench cannot simply be cleared
A teaching bench at the end of a day may hold work in progress for tomorrow's class, equipment deliberately positioned, materials set out for a demonstration, or student work waiting to be collected. Clearing it destroys preparation that took someone an hour and cannot be reconstructed from memory. Cleaning the clear portions and leaving the rest is the only rule that works across every room in a campus.
The consequence is that bench coverage varies by room and by day, and that should be stated. A room used for a practical class will have less accessible surface than a lecture room. Where a department wants full bench coverage on a particular day, the workable approach is a nominated day when the benches are cleared by staff beforehand. That arrangement gets a better result than adding frequency to a room that is never clear.
