Final answer:
Food-cost percentage should be calculated monthly to ensure business profitability and effective expense control in the restaurant and food service industry.
Step-by-step explanation:
According to the text, food-cost percentage should be calculated at least monthly.
Calculating the food-cost percentage is a critical aspect within the restaurant and food service industry, and this calculation helps businesses maintain profitability and control expenses. It's essential to do this calculation regularly to respond to any changes in the cost of goods or menu prices. The texts provided reference budgets and cost calculations such as calculating the cost of food in households and the implication of these costs on the poverty line, along with examples of monthly budget constraints.
These examples imply the importance of regular reviews of expenses, which corresponds to the practice of calculating food-cost percentages regularly, suggesting a monthly cadence.