6. Inventory eats up valuable stocks of materials and parts
We cannot make products out of thin air. We must have the materials and parts to make them. If we use our current inventory of materials and parts to make products that cannot be sold immediately, and therefore sit idly as product warehouse inventory, we have eaten up stock of materials and parts-the value of which will become painfully clear if a big order comes in for a different product that we now lack the components to make.