Ah, I see you're transitioning. Yeh, 400 litres sounds right for day's work on domestic; obviously factors depending.
As you get more experienced you will work faster; it just happens; and when your flow controller conks out, before you buy another, reconnect the pressure switch and have a go with no controller - just pump and battery (and a cheap on/off switch).
It gives a great flow of water, you can work really quickly, and there's no flow controller to mess you about.