It is best to discuss the customer’s requirements prior to the clean. Try to find out what their priorities are. That way both parties have a realistic expectation on what can be accomplished. If you are struggling to finish the areas you have agreed on with the customer, please speak to them directly to let them know.
If this is a regular customer, ask if they would like to to extend the booking time on your future appointments if you are happy to stay longer at the property.
If it is a one-off customer, they might ask you to stay longer to finish the remaining areas. This is entirely up to you. If you choose to stay, make sure you and the customer agree on the new duration. When you request the payment after the booking, make sure you let us know that the final duration changed so that it can be amended.