These are the people that are afraid that if they tell someone how they accomplish their job, that they will be replaced. To them, it’s job security that no one else knows how to do what they do. To me, that’s the worst kind of person for any organization.
I give my team the tools they need in order to do their job more efficiently. My hope is that as I fix and implement certain processes, that function/task will no longer require my “managing” and attention; the team will be on autopilot once everyone is equipped to successfully execute it.
When I learn something new, I share it. When I solve a problem, I share the situation and how I resolved it. Being replaceable means you are arming those around you with the knowledge you have. You are helping people work smarter and be more efficient by being an open book.