I remember losing a job some years ago for the following reasons:
(1) through not cleaning frequently enough
(2) not cleaning insides (I asked him to give me more notice rather than letting me know on the day)
(3) not clearing gutters (inaccessible job without a gutter vac)
(4) not de-mossing the roof when asked (this looked like a major job and one for which I was not equipped)
On its own, (1) might have been fair enough as I had been going through some difficulties that distracted from work. However, when added to the other reasons, I felt a need to point something out to him. This was that if I carried out those extra tasks for even a small number of customers, the gap between window cleans would be even longer - meaning that the things he wanted from me were in conflict.
This was part of the process of deciding to reduce my additional services. So, F/S/G exterior cleans and exterior conservatory roof cleans only. If it's not built in to an annual agreement, I need to be notified on the previous visit so that I can work it in. Sometimes I can do it on the spot if I'm in front with my work, but I tell them that I need some prior warning to guarantee that I can do it.