The cleaners did an average (fairly good) job as compared with other cleaning services I've used in the past 30 years. Given the person-hours (2) & the amount of preparation I did (removed decorative objects from shelves, emptying tubs and showers of toiletries printed list of prioritized tasks, conversation with cleaners regarding my expectations) I was not terribly impressed. An entire set of shelves I had emptied did not get dusted at all and some type of powdered cleanser was left in my MBR toilet.
My apartment is a 1400 sq. ft. 2-bedroom, 2-bathroom unit with a small kitchen and a living room. The person who cleaned for me most recently did a much more thorough job in the same amount of time. Prior to this I lived in a 3500 sq. ft. 5-bedroom 5-bathroom home & used a cleaning person regularly. Two people thoroughly cleaned the entire house in 2 1/2 hours.
I would recommend a well-defined cleaning system (order of tasks and assigned responsibilities) for your staff. I would also suggest discussing preferred products/cleaning methods with new clients.