When we got our wfp up and running 5 or 6 weeks ago I obviously did my own windows.
Forget the fact I have a w/c who I pay (yes I'm lazy) .... My windows get dirty very quickly especially if it is windy as I live on top of a hill and nearish to the sea. So every Sunday I clean my own windows with wfp to see if I'm improving and getting quicker.
The first time I was quite impressed and had a few spots but the last time I done them, last Sunday, they were spotless.
Just before it got dark this evening after reading the above I just rinsed the windows at the back and now that they are drying, they are a mess.
So .... my own experiment is that just rinsing fairly dirty and fairly salty windows doesn't work.
Well it didn't on my place at least.
Cheers