Hi Dazmond
Most of us who started with WFP many years ago had very basic equipment.
I started with a heavy Unger Ali pole, Shurflo 5 litre pump, 1/2" hose, no electronic controller and 2 x 3mm jets in a Vikan oval brush which I still have.
To start with we had very few WFP users to share experiences with so it was usually trail and error. I personally used to spend far to much time scrubbing and rinsing, so I could get through 500l by 4pm on a good day very easily. I had a trailer that had 3 x 125l tanks and would carry 5 25litre barrels in the van.
We now have electronic controllers, Minibore hose and 2mm jets, so use less water.
My son has gone from his van mount to using a backpack for most of his daily work as he finds it quicker than getting the hose out and dragging it around the back of his residential customers. Using the backpack has helped him spend less time on the windows to save water so now uses about 250l per day as opposed to 400-450l with the van mount. He is conscious of his water usage all day where I don't give it a thought. (I have a 650l 2 man setup on my van, but mainly work alone as we accomplish more separately than together.) He also does about 20% more customers than before.
I find that the flow at the brush with my Varistream on 3 is slightly low, and prefer to use 4 but use more water during the day as I still tend to spend too much time on the glass. I also don't have the stamina I once had, age and health related.
Spruce