You have to remember that you use less fuel for less water, and not everyone boils water every meal. I used about an ounce to boil .7 - .9 liter of water, half an ounce for half that amount. And if you filter the water first you don't have to get the water boiling, just hot enough for tea or rehydrating the meal. I do water at breakfast and dinner just for me and always had enough left to wash out the bowl, wash my hands and face, and a few ounces left over. Being more exacting about it would let you dial in on just what you need for fuel.

I've made a simmer cat (fewer holes) and taken it along too for steam baking or simmering on the few occasions that I do more than boil. You can get 15 minutes of burn time out of the same amount of fuel with a simmer stove.