Transformer core ordering- by Stack height, number of sheets/books or Weight?

In any Power Transformer Manufacturing Company, should the core be ordered on stack height (which is directly proportional to the cross sectional area of the core and therefore inversely proportional to the flux density), or on the number of sheets in each leg (which would enable production to efficiently assemble the core without shortages or mismatches in leg heights) or should it be ordered on a weight basis (which would enable the purchase to effectively control the costs).

As we can see from the preceding paragraph, there are three different departments of the organization which has competing priorities in this decision making. These three departments are the design department, the production department, and the purchasing department.