We've been WFP 6 years now and we had similar problems for about 3 of those.
We now no longer squeegee ANY out side windows.
We pratted about with the occasional old folks bungalow who resisted the change, squeegeeing them or drying off the WFP. But we stopped that now, Waste of time, effort and resources.
If I get a complaint nowadays it normally goes:
Cust: "1 of my windows was missed"
Me: "Oh sorry, is it dirty?"
Cust: "No but it's not wet"