One production order or multiple?

I have a BOM with 2 components and 2 assemblies. I have option to create 2 production orders for assemblies and one for FG. Or I can create one production order for complete BOM exploded instead of 2 orders for assemblies . The one production order can have multiple operations and 2 operations can be —- create assemblies with components assigned. Why do we need prod orders for sub assemblies? What can’t we create one prodn orders and include sub assembly as operations and components?