[upvotinglurker]

I worked at a franchised US Burger King in the late '90s. The shift manager would tell us how many fully assembled copies of each popular sandwich type to keep on hand. I never saw any charts or evidence of number crunching, but the numbers did vary based on expected traffic for the day of week and time of day, and the popularity of the specific item.

The sandwich wrappers had the numbers 1 to 12 printed on them, and you were supposed to mark the pre-made sandwiches to show when to throw them away. For example, if you assembled the sandwich at 12:15, mark the 5 to show that it should be thrown away when the clock's big hand is on the 5. Literacy not really required.