Leaders often talk about retention as though keeping everyone indefinitely is evidence of success. I think that can become selfish surprisingly quickly.
Some roles, most notably in my experience Senior Engineer, have a natural ceiling. There may be nowhere for someone to progress without their tech lead leaving, another team starting, or the organisation inventing a title that does not represent meaningfully different work. Keeping a capable person in their current position just because they are valuable to me might make my immediate problems easier, but it does very little for them.
So, I would rather plan for their departure.
In one team, I encouraged the tech lead to spend time solving problems outside the team. This created space for a senior engineer to step into more of the day-to-day technical leadership. The tech lead gained broader organisational experience solving bigger problems, the senior engineer gained evidence they could operate at the next level, and the team became less dependent on either person. Nobody needed to leave immediately for that investment to be worthwhile.
The same principle applies in smaller ways: inviting someone to shadow a meeting, asking them to represent the team with stakeholders, and then eventually stepping out of the call entirely.
Planning for departure means maintaining a pipeline of people at all levels who are being given opportunities to grow into greater responsibility. It means making sure important knowledge is shared before somebody hands in their notice. More importantly, it means having honest conversations with people about what they want, including when I suspect they will eventually need to find it somewhere else.
A succession plan can sound cold when applied to individuals. I don’t want people to feel that I am preparing to replace them while they are still doing the job. It needs trust and an understanding of everyone’s long-term career goals.
The point is to avoid making somebody indispensable and then quietly punishing them for it. If their departure would leave the team unable to function, I have created a reason to obstruct their progression. That is a failure in how I designed the team, not evidence that they owe me more time.
There is also a more personal measure of success here. When somebody leaves my team, I want to be able to wish them well without privately resenting the problems their departure creates. I want them to feel comfortable telling me they are considering another opportunity before the decision is final.
I won’t always be able to offer someone their next role, but I can make sure that their time working with me helped prepare them for it. If someone cannot leave without damaging the team, I have failed both them and the team.