Hi Paul
You can rinse on glass with pencil jets you have to tilt to the side on glass this still involveps a sideways move whilst controlling the pole, It can affect wear on shoulders
With fan jets you scrub as normal, then back to top whilst brush on glass you repeat bring down or some I imagine you scrub and rinse as you go depends on preferred method
I find hard with a flocked style brush others might prefer, we all have our preferred brushes
I prefer the blue Wight ultra light gardiners hard to have with fan jets although I've just found some ebay work well just need bigger hole
If your shoulders have had it by end day, you need to evaluate what pole you use and what brush, the obvious answer is as light as possible to do the job satisfactory or as you can afford