Google announced you can now apply audience lists to the campaign level now. Previously, you were only able to add these audience lists on the ad group level, which could be terribly time consuming.
Campaign-level audience lists also make it easy to measure and change your bid adjustments. Instead of trying to change your bid adjustments for each individual ad group, you can confidently optimize at the campaign level where you’re more likely to have enough data to make an informed decision.
Here are some best practices for using audience lists in Google.