Using recipes from previous participants is handy because it already gives the cost break-down per serving. But just as when you're trying to diet and you become aware of servings versus helpings (what you ACTUALLY take and eat), I had to be aware of how many servings I was eating.
And example is the Cabbage and Potato Casserole. I ate two servings of this dish (minus the bacon) so had to calculate that into the day's dollars.
An example of a packaged item that I had to be aware of was cereal. I eat dry cereal with milk most days for breakfast. Most cereals give servings in 3/4 cup but I always eat 1 cup so I had to do the math to figure out how many servings per box instead of going with the number given in the nutrition label.