You're good with figures wally.
I've never ever understood this idea of Jeff's.
The ratio i look at is water to time, and time to money,i'm a 600l kinda guy,and i work fast.
Not saying what i do is right, but i work to earn money, and the more i do in the least time the better.The high flow does much of the work for me.I'm on q meter- this is about £2 a day, and hot is another £1,- so for £3 i get to splosh for dosh.