I have had problems with spotting on certain windows, the ones that “sheet”; don’t cause problems, the ones that turn to rivers, do. This is despite giving an extra rinse to the ones in direct sun. Have had to go over a few today that had dried spotty at the top. I had a complaint a couple of weeks ago, when I went to collect, customer said the windows were dirty after air had been. I’m offered to do them right then, but she declined as had friends round. After a bit of questioning, I put it down to the glass drying took quick. Is there any way to avoid this, or just a hazard of the time of year?