I give em a good clean on the first visit and then all they need is flashing over from then onwards,one of the many things that is good about WFP is that You can kiss goodbye to those green window sills,it was hard work doing frames and sills trad way but when You have got them clean WFP like i say just a quick brush round the frame keeps them looking good,with wooden frames unless there in very good order paint wise i only do the glass and stay away from the frame.