Sometimes i dry cills with a cloth. But only on new work when debris keeps coming out from that recess, no matter how much time i spend brushing and flushing. Otherwise i don't see the point.
I have been told by a couple of customers before, that their brother/sister/pet dog's window cleaner wipes the cills. Why don't i?
I tell them i don't because the cills will get wet anyway until the window has dried. They seem to have accepted this. For now.