Why is it recommended to separate Display Network campaigns from Search Network campaigns?
- Different campaign settings may be more effective on different networks
- Separate campaigns allow for more accurate location targeting
- Higher bids are required to be successful on the Google Display Network
- Lower clickthrough rate (CTRs) on the Google Display Network can negatively affect Quality Score
Each bid strategy is suited for different kinds of campaigns and advertising goals. For the purposes of bidding, you’ll want to consider four basic types of goals, along with your current campaign settings.
Read more here: https://support.google.com/adwords/answer/2472725
Separating campaigns by type is a good practice as it gives you much more flexibility targeting, bidding and optimizing your campaigns.