“How many people should be “in charge” of a digital sign?”
There isn’t one number or structure that works the best. The better the command and hierarchy, the better the communications and expectations though. Someone, or a team, should at least be in charge of content and programming. If they are on vacation or leave, you need an apprentice or back-up. So at least two!! Then someone needs to understand the network, infrastructure and hardware. That can be divided out for big organizations. This too needs a back-up plan and structure. I’ve seen some businesses have one IT person and one content person for a large setup. I’ve seen other organizations have 10 people per chain of command with email aliases etc. The bigger you are, the more documentation and structure is needed to get things done. Being small and nimble means that scaling will be more difficult. In some cases, just for content, groups interject an approval process, which has more people and process. Review your growth plan, review your risk and data plan and determine your team knowledge before you start installing digital signage.