You can get an alcohol burner to boil fast, or you can get one to boil very efficiently on less fuel, or you can get one that weighs less. Take your pick.
You might be able to add in a cost factor, if that applies.
When you are looking at the weight of an alcohol burner, the fuel efficiency becomes a weight factor, so you end up having to estimate the total weight of burner+fuel for a given trip length.
It is not a one-size-fits-all solution.