Jeff is the exception that
'probes' the rule!
Few will manage what he has done.
A way of making your water go further is of course to reduce your flowrate, but with a low flowrate (Jeff being the exception) you have to work slower as the flushing of the glass is of course far less than you can get with a higher flowrate.
Work too quickly with a low flowrate and unless highly skilled (re Jeff Brimble) the quality of your work will suffer (spotting etc).
One of my batteries is misbehaving, my flowrate has dropped considerably, I don't mind too much at the moment, but I have noticed that I've had to take more time.
Occasionally it fires on all four so to speak, flowrate is right back up there again and suddenly I'm working half as fast again than I was before.
But that also requires skill -to work fast with a high flowrate - so you need to be able to temper your flowrate to your workrate.
Therefore you also need to be able to increase or decrease your flowrate accordingly....
If you are working with a backpack, a high flowrate will have you constantly needing to refill
If you only have a relatively small tank in your vehicle, you will be hampered by the thought that if you use a high flowrate you are going to run out of water, and that will affect the way in which you work.
You can never have too big a tank (loading values notwithstanding of course) so don't go for the smallest tank you can get away with, go for the biggest.
Ian