I'm happy Sean to explain why higher flow is better, quicker and gives great results time and time again, and yes I've done tests and have experience of using low flows to know you are more likely to have spotting!
Firstly with fan jet you can keep ramping up the flow, why? Because water is forced out in an arc along the horizontal plain, unlike a pencil jet which mushroom on impact ( this is where it pushes dirt upwards ) with fan jets you get a curtain of water along the brush head, so you are cleaning and rincing a whole area with one movement and the brush requires less movement because the water inside is edge to edge, with pencils you to move the brush more ( as per your video ) to cover the glass, and more slowly, the slower the flow the slower the rince because to need to allow for the trickle of water and the tiny surface area it's covers time to actually make contact with the glass, likewise you need to zigzag down over the glass, with high flow you get a water curtain effect so you can for most windows rinse at the top then move on.
With fan jets you can rinse with brush on or off ( about 1") a tap, aquadaptor aquatap are all ideal add ons for quick on/off for water, rincing with pencils usually means holding the brush head 3 to 6 inches away from the glass, (less control)
Very early on I studied the 2 techniques - Jeff bramble the master of DIY and water saving and Peter fogwill who's autobrush lead the way with high flow WFP.
It became clear that those with low flow were doing so because they mainly needed to make the water last as they worked from backpacks and trolleys, they were prepared to work as close as they could to bare minimum boreline flow to save changing or refilling more often, with van mounts you can up the flow, water saving is not so high a priority as it once was.
On a personal level, I use high flow, but not full bore, there is a sweet spot (for me) where you can only cover so much glass without wasting water but the flow being such rinsing is almost instant.
Here are some examples for you - in pressure washing you can use 15 deg spray tips these give deeper clean but are slower because they cover a small area and stripe easily, 25 deg tip covers a larger area, work is done more quickly but is less intensive, now your using pencils and trying to ridicule the use of high flow when in truth you are using a jet more suitable for heavily soiled windows rather than maintenance work
If you have a patio with leaves on, try hosing it down with a single jet at low flow then with a higher flow on a fan setting as see which covers and cleans the fastest.
hope this helps
Darran