Picture the most capable leader you've worked for. Now ask a harder question: when they left, did the team get stronger or weaker? A surprising number of admired leaders leave a hole, not a bench. That gap, between being good at the job and leaving behind people who are good at the job, is what legacy and succession thinking is actually about.

The quick version

  • Succession is a development practice, not a paperwork exercise. Naming someone "the successor" changes their title in a spreadsheet, not their readiness.
  • People grow mostly through the work. Research from the Center for Creative Leadership puts roughly 70% of leadership growth in challenging assignments, so legacy is built by what you delegate, not what you lecture.
  • Build the pipeline early, internally, and often. Companies that plan ahead promote from within; the ones that scramble pay for it in lost performance and value.
  • The honest test of your legacy is the year after you leave, not the quarter you're praised in.

The idea in depth

Legacy is a leadership factory, not a farewell speech

The most useful reframe here comes from Jim Collins's Good to Great research. Collins found that the leaders who built enduring, high-performing companies, his "Level 5" leaders, combined deep personal humility with fierce professional will, and pointed that ambition at the institution rather than themselves. One striking pattern: of the eleven good-to-great companies he studied, ten promoted their next chief executive from inside. The comparison companies reached outside roughly six times as often. Insider promotion wasn't a coincidence; it was evidence that those organisations had been quietly manufacturing leaders for years.

So the move is: stop thinking of your legacy as the results on your watch, and start thinking of it as the readiness of the people on your bench. A practical version: keep a private "who could do my job, and what's the one gap between them and ready?" note for your two or three strongest reports, and revisit it every quarter. If you can't name the gap, you don't yet have a successor, you have a hope.

An honest limitation: Collins's work is correlational. It identifies patterns in companies that thrived, but it can't prove that insider succession caused their success rather than accompanied it. Treat "develop insiders" as a strong default, not an absolute rule, sometimes the team genuinely needs an outsider's break from the past.

The pipeline is plumbed by the work you hand over

If legacy is a factory, what's the production line? The most evidence-backed answer is experience. The Center for Creative Leadership's long-running Lessons of Experience research, the origin of the well-known 70-20-10 model, found that managers attribute roughly 70% of their development to challenging assignments, about 20% to other people (coaching, mentoring, role models), and only around 10% to formal training. The numbers are a rule of thumb, not a law of physics, but the direction has held across decades of interviews: leaders are forged mostly on the job.

That reframes succession from a planning problem into a delegation problem. The work you keep because "it's faster if I do it" is precisely the work that would have stretched your successor. Stephen Drotter, Ram Charan and James Noel make the same point structurally in The Leadership Pipeline: every step up the ladder demands a real change in what you do, how you spend your time, and what you value, and people only make those transitions by being given work that forces them.

So the move is: deliberately hand a high-potential report something genuinely above their current grade, a decision you'd normally make, a stakeholder you'd normally manage, a problem with no clean answer, and then resist rescuing them. Pair it with the 20%: a short, regular debrief where you ask questions rather than supply answers (the GROW model is a clean structure for exactly this). The assignment does the developing; the conversation does the harvesting.

An honest limitation: the 70-20-10 split is a memorable average, not a prescription you measure against. Stretch without support becomes sink-or-swim, and stretch without reflection just produces a busy person who didn't learn much. The percentages matter less than the principle: real responsibility, then real reflection.

flowchart LR
  A(["Challenging
assignment (~70%)"]) --> D(["A more
capable leader"])
  B(["Coaching & role
models (~20%)"]) --> D
  C(["Formal
training (~10%)"]) --> D
  D --> E(["Ready successor,
not just a named one"])
The 70-20-10 rule of thumb: development is mostly the work, lightly the people, barely the classroom. Leaders Loop

Naming a successor is not the same as having one

Here's where good intentions usually break. A board or a manager identifies a "high potential," ticks the succession box, and quietly assumes the development will sort itself out. It rarely does. In their 2021 Harvard Business Review article "The High Cost of Poor Succession Planning," Claudio Fernández-Aráoz, Gregory Nagel and Carrie Green argue that many large companies pay too little attention to their leadership pipelines, and that the resulting churn at the top destroys substantial shareholder value. The expensive failure mode isn't having no successor, it's having a name and mistaking it for a plan.

So the move is: for anyone you've earmarked, write down the specific experiences they still need before they'd be ready, a P&L they've never owned, a crisis they've never run, a team they've never had to rebuild, and then go engineer those experiences on purpose. Identification is the cheap half of succession. Development is the half that costs you something, which is exactly why it's the half that works.

An honest limitation: the dramatic value figures attached to executive transitions come from studies of large public companies, and the precise numbers vary by method and dataset. Don't quote a specific dollar amount as gospel. The defensible claim is directional and well-supported: poorly prepared transitions are reliably costly, and preparation reliably reduces that cost.

flowchart TD
  A(["Identify a
high-potential person"]) --> B{"Named, or
genuinely ready?"}
  B -- "Just named" --> C(["Box ticked,
gap untouched"])
  C --> D(["Scramble & cost
when the seat opens"])
  B -- "Named + a real
development plan" --> E(["Stretch assignments
+ coaching"])
  E --> F(["A successor who can
actually do the job"])
The expensive gap in most succession plans sits between "named" and "ready." Leaders Loop

A worked example

The figures and names below are illustrative, a composite scenario, not a real case study.

Maya runs a 30-person customer-operations group. She's excellent, visible, and, the board has noticed, a flight risk for promotion. The unspoken assumption is that her deputy, Tom, would "obviously" step up. Tom has been Tom's manager's favourite for three years and has never once owned a budget, run a board update, or made a hiring decision that mattered. He is a named successor and a non-existent one.

So Maya stops protecting him. Over the next two quarters she hands Tom the annual planning round, he builds the headcount case and presents it to the leadership team himself, with Maya in the room but silent. She gives him a struggling sub-team to turn around rather than the easy wins he usually gets. After each, they spend forty-five minutes debriefing: not "here's what I'd have done," but "what surprised you, what would you do differently, where did you feel out of your depth?"

Six months later Tom is not a finished leader, but the gap is now visible and named ("he avoids hard conversations with peers"), which means it's workable. If Maya is promoted tomorrow, the team inherits someone who has already done a credible version of the job, not someone discovering it for the first time on day one. Maya's legacy isn't the dashboards she leaves behind. It's Tom.

Frequently asked questions

Isn't succession planning only for CEOs and big companies?

No, that's just where the eye-watering numbers come from. The mechanics are identical for a team lead: who could do your job, what's missing, and what work would close the gap? A front-line manager who develops one capable successor has practised exactly the discipline a board spends millions trying to get right.

Won't developing my successor make me look replaceable?

That fear is the single biggest blocker, and it's backwards. Leaders who hoard the critical work make themselves un-promotable, there's no one to leave the job to. The ones who build a bench are the ones organisations feel safe promoting, precisely because they've proven they leave things better staffed than they found them. Replaceable is the prerequisite for promotable.

How is this different from mentoring?

Mentoring is one ingredient, the "20%." Succession thinking is the whole recipe: the stretch assignments (70%), the developmental relationships including mentoring and sponsorship (20%), and targeted training (10%), all aimed at producing readiness for a specific future role. Mentoring grows a person; succession thinking grows a person into a particular gap.

What if my best candidate still isn't ready when the seat opens?

Then you've learned something useful early rather than late, and you have real options: an interim arrangement, a deliberate outside hire to buy development time, or an accelerated stretch. The failure isn't "not ready yet." The failure is reaching the day the seat opens and only then discovering nobody is close.

How do I find time for this when I'm already underwater?

You don't add time, you redirect it. The work you delegate is the development, so the hours move from you to your successor rather than appearing from nowhere. The only genuine extra cost is the debrief conversation, which is cheaper than redoing the work yourself and far cheaper than a failed transition.

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