You're not done teaching until the expertise on your team outweighs your own capabilities.
Of course, this makes perfect sense on the outset. If each of your team becomes a deep subject matter expert in their assigned area, then it makes it that much easier to delegate work to that person.
However, this creates two problems, at least, they're perceived (and sometimes real but only by bad executive teams):
When senior leadership wants to praise someone for project X, your team member gets the glory, not you.
You seemingly make yourself redundant. I mean, the team knows more than you do. Why do we need you anymore?
On the first one, I would say, "Get over it." When your report gets praised, it's praise for you too, or at least, it should be. On the balance, it's a positive for you. Because they're getting exposure to senior management, when it's time to argue for raises or promotions, it's a lot easier when your reports are known (in a positive way) by the senior management team.
On the second point, this is trickier. I've personally witnessed and been affected by senior management teams that are too stupid to realize what's really happening here. My observation has been that senior management teams who themselves are poor managers typically make the mistake of assuming redundancy once a team is "smarter" than their boss.
Here's what happens when a good manager is replaced with a poorer one:
- Lack of clarity on roles and responsibilities - It's the manager's job to make sure their reports know what they're responsible for delivering at all times. Poor managers tend to be vague. (This is a bit harder if you're managing an executive team where the scope and responsibilities are purposely vague. In this scenario, I'd say a good manager should set clear goals for each executive manager.)
- Accountability issues - Poor managers hold reports accountable in an haphazard and inconsistent manner.
- Attrition - While the good manager took the time to find professional development opportunities, teachable moments, and perhaps even structured exercises for his/her reports, the poor manager does not. HR studies have shown that pay is not the reason why people stay. Many stay because they feel like they have more to learn. It's also a commonly repeated statistic that 80% of people quit because of their boss. The flip side of that statistic means that when people stay, it's because of their boss.
There are many more, but the point is that a good manager keeps teams together and performing at a high level. I've had a number of managers who were good teachers and were almost the sole reason I stayed in a position. While I was at Yahoo!, my group was led by a VP who used teachable moments like a scalpel and made working for him fun and exciting.