Try hot to I dont have a slow rate mind! i have to have it on 4 to get the boiler fired up. I just really dont know how you guys use so much water.
higher flow = quicker rince iv helped mark with a few houses hear and there and his flow is painfull takes me ages to clean the windows properly in comparison to my flow setting and when i moaned to mark lol he said yours is even slower. but i use gardiner fan jets mite make it different, i also understand that you may be on a meter and when im eventually on one my attitude will change im sure.
get a set of gardiner fan jets and turn your flow up a bit more probley number 6 on the varistream id say on one real that is you watch how many more houses you will do honestly mate you will do more an hour just have to push the pole a bit quicker to match the flow
Lack of confidence=higher flow=quicker rinse.
Confidence=lower flow and very little time spent wasted on rinsing.
There's a good video that pops up on here every so often of a guy cleaning windows very quickly, it shows how little the amount of rinsing you actually need to do this job and how quick you can become when you have the confidence.
Hold your brush off the glass and watch how the water hits it, you will see that a large amount of water never touches the
glass even with a low flow.
Don't get me wrong I'm not saying there wont be times when you will need to use more water very dirty first cleans is one
example but like I keep saying there's very little dirt on a four weekly maintenance clean.