AdWords is complex. First time users that open up an AdWords account feel like they’re looking at the controls for a spaceship. The hundreds of options and settings can be overwhelming. So, it’s understandable that sometimes people miss things when running an AdWords campaign.
It’s not just AdWords newbies that have this problem. Even veteran users can sometimes get too comfortable and miss a small detail if they aren’t keenly aware that they could be missing something.