My biggest mistake in setting up was to go eight weekly, I did charge either £8 or £10 depending on the size of the house but each time I visit its like starting over again.
I do have a couple of monthly cleans which are just so much faster to complete.
I did a course years ago at the BWCA and they said just sweep to applicate no need to scrub on regular cleans, with eight weekly I still have to scrub the windows.