I have a couple of jobs with sash windows. I 'phone them the night before.....standard, they are a nuisance, (after a call I get them to reverse the window position)...that is to say...the top window is proud compared to the bottom one. This is better with a pole. However, if the top one is recessed....it's a lot worse..those using poles will understand what I mean...not sure if that helps...but at least gravity and water ingress is not working against you...
Sorry, doesn't read well..but I hope you get the drift....