Please tell me you are doing this.
The Search and Display Networks are two very different things. The Search Network is active or intent-driven. The Display Network is passive or interruptive.
What does that mean?
With the Search Network you are actively engaging with people who are looking for the service(s) or product(s) you provide. Someone makes a conscious decision to enter a specific search term into Google. If you have said keyword in your keyword inventory, then your ad appears. A connection is made and they click.
With the Display Network, its more like old school television where there you are watching your favorite program and suddenly a commercial interrupts your enjoyment to try and sell you something. For those of us old enough to remember when television was a handful of stations, this was the time when you either went to get something to eat, took a bathroom break or maybe changed the channel. Sometimes however said commercial was visually interesting enough or the offer tantalizing enough that you’d pay attention. Google’s Display Network is a lot like that. You’re doing whatever you’re doing online, not thinking of buying anything, and some display ad appears and tries to grab your attention. You might be interested but are not actively so.
The problems (and they are plural) with running a Search & Display Networks campaign include:
You pay the same price for the Search Network’s high intent traffic (ie people actively looking for you) and the Display Network’s low intent traffic (people not looking for you).
You use the same ads for people searching for a specific keyword and people browsing a website that may be on a completely different topic.
You use the same keyword structure for both networks when these networks require different approaches to segmenting keyword lists. This results in large volumes of wasted spend on the Display Network.
Using the Search & Display Networks campaign option means that you are unable to use a number of advanced feature. Features unavailable under the combined setting include advanced language targeting, location and social settings, mobile app extensions, and IP exclusions.
In a nutshell: It is always better to build standalone Search and Display Network campaigns.