Productivity moves in the opposite direction to rate
Cleaning an occupied office takes materially longer than cleaning an empty one. Desks cannot be reached, meeting rooms are in use, floors cannot be treated across a route people are walking, and every task is interrupted. The same work can take half again as long in-hours as it does after hours, which means a lower hourly cost does not automatically produce a lower total. That difference is a genuine feature of the building rather than something a provider is choosing to charge for.
The effect is strongest where the premises has enclosed rooms, meeting spaces or public areas. It is weakest in an open warehouse or a premises where most of the cleaning is amenities and circulation, which can be done around people without much loss. That is why the answer differs by building rather than following a general rule about which option costs more. Asking for both to be priced against the same task list is the only reliable way to see which suits your premises.
