I have about 20 houses each month where the paint is flaky and the frames are rotten in places. I haven't had 1 problem with the finish. Not 1.
I was expecting to have to pass them on when i started wfp, but the only problem i have found is that they need alot of rinsing.
If not rinsed well there are little bits of paint debris that fall down the window a bit then stick.
I can do a much quicker better job by scrubbing the frames on these houses than by just trying to clean the glass.
High flow rate, broad sweeps of the brush, a good rinse, job done.
Wooden windows on barn conversions are the ones that i have had probs with. But these are treated with stain or something.