My system has a pump box with a by-pass loop that lets me regulate the flow from about 1 litre per minute to 3 litres per minute. I run on 1 litre per minute. Although this means a slower rinse rate I don't inadvertantly splash brickwork, vents and tops edges of the frames.
I also have a remote on/off switch which I use as well.
I nearly always blade doors especially now water left behind might freeze. Patio doors too sometimes.
Lower cills I wipe off with an old towel instead of the brush.
I use 150/200 litres in a day tops, unless I am doing a commercial to start with.
I have not lost a domestic or commercial customer since February when I started wfp.