How do you decide when a preorder date is full?

For small-batch producers, capacity is rarely one number. An oven, mixer, production day, staff availability, pickup window, and individual products can all become the limit.

At Ember Bakehouse, that pushed us beyond a simple maximum order count. We needed product limits and shared capacity across items that use the same production resources.

When you decide a pickup or delivery date is full, what rule do you use today: total orders, total items, product-specific caps, production hours, equipment capacity, or judgment?

I am interested in the real rule businesses use, including the messy version that lives in someone's head or spreadsheet.