Specify your content requirements for your campaign (e.g. black hair, male, degree of smiling etc.) to an automated algorithm and get a set of images instantly. If you are not satisfied, change some words and get new results. A paper by Adobe researchers:
"The design and content of contemporary marketing campaigns, websites and banners have become increasingly targeted and sophisticated, and compelling image content is crucial for companies striving to stand out from the competition. Human graphic designers can spend a great deal of time iterating back and forth during a laborious content creation process that includes selecting, editing, polishing and compositing raw images to create satisfying and effective marketing content."