I have found that just washing the whole window , frame and glass every time is the best way , do the frame and glass then finish the agitation at the top of pane, lift off go left and right once then move on .
No matter what your way is , surely if you skip the top frame on any clean you are kind of inviting spotting , why not just spend those extra few seconds per window and walk away safely knowing all will be good .
You are in fact saving 20 seconds per average 3 bedder , but in reality are opening the door to a possible cancelation due to the fact that WFP does not work as well , why would you risk that to shave 15 minutes off the day ?