Guests form an opinion of a venue fast. A tacky floor by the taps, a bathroom that smells by mid-afternoon or a courtyard still dotted with last night's cigarette butts is enough to send them somewhere else next time.
Most venues have the same squeeze. Trade finishes late, the doors open again for lunch, and the gap in between is short. A cleaner who treats the place like an office will do the visible floor and skip the rest: under the bar stools, the TAB corner, the stairs to the function room, the staff corridor by the cool room.
The cost lands on your own team. Bar staff arrive and start wiping down before they can stock the fridges, and the duty manager spends the first half hour on a cleaning walk-around. Over a year, that adds up to a lot of paid hours.