And this secret size is...4 oz?
We have answers of 10 -14 meals and 27 -30 meals. In hope one is for 4 oz and one for 8 oz. Otherwise, no assumption is safe.
I think it is safe to assume that 2 people cooking twice a day are using the larger 8 oz cylinders. They are more stable and weight efficient than the small cylinders. Certainly, a significant number of couples carry 4 oz cylinders, especially as a backup cylinder. It sounds like this couple is cooking 4 meals/day and another 4 cups (2 meals) for drinks. So, the 27 - 30 meal cylinder may not last 5 cold days.
Rambler