Access assumptions that change the price
Cleaning an empty floor is faster and better than cleaning around people. If the scope does not say when the premises are available, a bidder must guess, and the cautious ones price for the harder scenario while the optimistic ones do not. That single unstated fact can produce a spread between quotes that looks like a difference in efficiency but is really a difference in assumption.
Entry method matters almost as much. A key safe with an alarm code allows an early start; waiting for a manager to open up ties the visit to someone else's day and adds unpaid standby time that ends up somewhere in the rate. Say plainly how the cleaner will get in, who holds keys, and what happens when the usual contact is away. A named backup avoids the visit being lost entirely when one person is unavailable.
