Today I did something my father never did for me: I helped my son prepare two second story wood windows at his house in Guelph for painting. We removed the loose and flaking paint and I caulked around the outside and applied a coat of primer to each. It appeared to me that the windows had never been painted since they were installed when the house was new, perhaps a decade or more ago. There were no traces of paint on the plastic slide part of the inner window. Perhaps you can get away with this on the south side of the house—the wood drys out too fast to rot. But they did look terrible with the peeling paint and greyish frames.