Carry enough for two days. I haven't been using the kettle yet as I've been trying this, which is too slow.
I figure on carrying the kettle across the top of my pack. It'll boil a litre of water as quick as a household electric kettle. I've got two, large and small. The large is best because you can get more fire in it, and a good amount of hot water for washing up. The whole cook kit is good as well.
I aim for 20 to 25 miles per day, but age is catching up. The old cattle drovers would cover up to 50 miles bare foot on the return journey after driving their herd to sales.