There are four main categories to think about when you categorize your keywords into campaigns: retailer, manufacturer, product and category. And then there are the multiple inter combinations of those four.
Prioritizing which category you should focus on depends on which category your business falls into. If you’re a brand manufacturer than the Manufacturer bucket will give you the best return and you wouldn’t worry about the retailer category. If you’re a retailer without your own brand than you need to worry about all four categories. Generally ROAS and volume looks something like this (varies depending on industry):