Id say about half my round is wooden framed sash windows on Victorian and Georgian properties, as above main problem is the flaky paint ones. I do find sash frames a problem sometimes, its easy for dirt trapped between the frames to leech out on to clean wet glass.
My brush has two sets of jets used independently, fan jets and 1.4 mm pencil jets.
First cleans I will use the fans on full flow for frames, once they stop dripping I clean glass with the pencils on a lower flow and subsequent cleans.