Clever service! I assume your employees watch several people at once. Is it engaging enough work for them?
Also, we do more than just body doubling. Some clients need to follow a morning ritual before starting their work (think meditation, a quick house cleanup, etc.). Sometimes, we perform sanity checks on their to-do lists (people often create tasks that are too vague or vastly underestimate the time needed to complete them). We ask them to apply the 2-minute rule, and so on. It all depends on the client's needs.