Use no more than two extensions per campaign or ad group. Use at least five extensions and add only to ad groups. Use ad extensions only when advertising the service industry. Use at least three extensions in each campaign or ad group. Download Google Ads Search Certification Exam Answers (PDF)
It’s better because the correct bid can often be a hard-to-reach static target. It’s better because user intent and the likelihood to complete valuable actions for your business don’t change according to location, time, or device. It’s better because the increasing complexity of the customer journey necessitates that bids be based on general user behavior. […]