This may be the biggest mistake a People Manager can do, which goes directly against Principals of Managing #2: Be selfless when managing: hold on to ALL People Management responsibilities and not delegate any.

This harborer of responsibility is usually driven out of a need for self preservation. Since this person is no longer a valuable Individual Contributer, they fear of not contributing enough and think they need to do everything that an IC wouldn't normally do. This is wrong.

“Your most important task as a leader is to teach people how to think and ask the right questions so that the world doesn’t go to hell if you take a day off,” says Jeffrey Pfeffer, the Thomas D. Dee II Professor of Organizational Behavior at Stanford University’s Graduate School of Business and author of What Were They Thinking?: Unconventional Wisdom About Management.

Have you ever heard of the "bus factor"? Essentially, how many people need to get hit by a bus in order for a catastrophic failure to occur on a team or line of business. If the People Manager is the only one handling management tasks, and the ICs under them aren't learning and developing in this area, then the bus factor for that team's failure is one...

This takes us to Principle #3:

Always be leaving

The phrase, "Always be leaving," is not meant to be taken too literally. The idea is to prepare the team for your eventual departure (hopefully to a new role in the same company!). To do this, the People Manager needs to delegate responsibilities to other team members. The People Manager should only focus on tasks that they alone need to handle. As stated in Software Engineering at Google: Lessons Learned from Programming Over Time:

… it’s not just your job to solve an ambiguous problem, but to get your organization to solve it by itself, without you present. If you can do that, it frees you up to move to a new problem (or new organization), leaving a trail of self-sufficient success in your wake… leading a team of teams is often more about organizing people rather than being a technical wizard.

A People Manager might find that there are people already on the team with the skills and desire needed to contribute in other ways; but there will definitely be instances when the People Manager doesn't have anyone on the team that is ready to take on more responsibilities. This is when the People Manager really earns their pay. A good People Manager can identify who would be good at what, which is the raw material needed to forge a future leader in the organization. These discoveries are usually made through frequent 1:1 conversations. Getting to know the team members is absolutely crucial in identifying these raw materials. The People Manager shouldn't leave it entirely to the team member to express a desire to grow in a certain way, just as they shouldn't ignore the team member when they express interest in developing in different ways. The real trick here is growing the team member without giving them too much or (in most cases) too little.

The fear of being seen as "useless" is what often leads to People Managers delegating too few tasks. This fear is typically fed by seeing complacency in other managers within the organization and hearing the whispers of how those managers are basically just taking up space (and pay). Complacency is a real concern for anyone, and it is definitely not something a People Manager ever wants to experience. But delegating tasks to others isn't the gateway to complacency; delegating is the pathway to contributing at a higher and more meaningful way. If a People Manager is good at what they do, then they inevitably see and know of holes higher up the command chain that need filled. Growing through delegation is how the People Manager's team will become self sufficient so the People Manager can focus on growing their own career.

Conclusion: Always be leaving is the key to being a selfless manager

A People Manager planning for their inevitable departure is one of the best things they can do for their team. It puts lower-level team members in a position to take the next step in their careers, and it gives the People Manager time back to focus on their own career growth. Delegating work is not the pathway to complacency and irrelevance, but is the pathway to success for the whole team and the organization.