The task that most likely belongs on the art director's schedule would be focused on the visual aspects of a project. This could include tasks such as:
- Reviewing and approving design concepts or layouts
- Meeting with graphic designers to discuss the visual elements of campaigns
- Conducting photo shoots or overseeing the selection of imagery
- Collaborating on the visual style of advertisements and promotional materials
Among these tasks, "reviewing and approving design concepts" would be a key responsibility that distinctly falls under the art director's purview.