Right now the only way to know which plans are sending out email reports is to check each plan individually. As the number of Plans and Tests grow it can be hard to know if you are sending out too many emails or not the right reports for the current time.
Maybe a separate Left Nav Topic call Reports? Could include managing groups, so if you don’t want all workspace users, you don’t have to add someone new to each Plan report setting. If not on Left Nav, maybe a new filter setting on the Plans page with a new column for report settings and/or a report toggle to change at top right, next to Enable, Disable.