How should primary versus secondary unit of measure be set for dual unit of measure items?

Summary: Determining primary versus secondary UOM setup.

Content (required): We are implementing Oracle Cloud for a manufacturing company in the food manufacturing business. Our in-process (WIP) and sellable Finished Goods (FG) items are set as dual unit of measure items. We track our items in cases (units) and pounds. For example, 1 case/unit of product could weight 10 lbs. We are not currently implementing Cloud's shop floor functionality, we are using an internal shop floor system. What is the best way to determine what the item's primary verses secondary unit of measure should be in item setup? Should the lowest level, pounds, be set as the primary? This is