A good manager notices when the reliable person has become everyone’s backup plan.

Reliability attracts work the way a low spot attracts water. Each request is reasonable on its own, and nobody is deciding to overload anyone; it is simply that the person who always says yes is the fastest route to a solved problem. Over months that adds up to a job nobody designed and nobody can see.

List what the steady person is actually carrying, including the things that never appear on any plan. Move two of them, and say why in front of the team. Then check whether the next request goes to them because it fits, or because they are easy to ask.