The other point we often overlook Mike is glass condition and frequency. Check out Trad Man in the U.K. His first clean workflow is night and day to his regular work which seems even on domestic to be monthly to six weekly. If I was doing houses monthly over here it would be a dream. In the city here our water is soft and has lowish TDS (60-80) so the glass, even when dirty and dusty is relatively pain free to scrub and blade. However less than 15 minutes away we have a town where the water is hard, and the glass, especially modern glass, invarably has a 'rough' feel on the surface from contaminants and/or calcium spotting and because our cleans are quarterly at most, every clean is like a first clean. Blading feels like running across fine sandpaper and any small error in technique gets punished. The worst glass in the town is the stuff from about 30 years ago that are in the early bronze Aluminium frames which themselves are calcified pitted and tend to eat rubber... so... maybe this needs to be taken into consideration as well when we find the tools aren't performing as well as we'd hoped.