Every debate about flattening eventually hides a number. Span of control, the count of people or teams one person oversees, is the quiet variable that decides whether a flat structure is a functioning design or a slogan. Push it too far and you get abandonment dressed as autonomy. Set it with care and you get an organization that genuinely runs without a middle layer.
The most instructive number in the field belongs to Buurtzorg. The Dutch home-care company supports more than 900 self-managing nursing teams with only 21 internal coaches, roughly one coach for every 45 teams, and those coaches hold no formal authority and carry no responsibility for the teams' productivity (Martela and Nandram, 2025). Set that against a conventional hierarchy, where a supervisor might oversee six or eight people with direct accountability for their output, and the gap is not incremental. It is a different category of organization.
The ratio that makes flat work
A one-to-forty-five support ratio is only possible because the coaching role is not a management role in disguise. A Buurtzorg coach does not approve decisions, set targets, or own results. That is what lets a single person serve dozens of teams: they are a resource the teams pull on, not a bottleneck the teams route through (Martela and Nandram, 2025). The moment you attach accountability for output to that role, the ratio collapses back toward the traditional span, because accountability requires attention, and attention does not scale to 45 teams.
The teams carry the rest. Each Buurtzorg team is capped at about 12 nurses and governs itself: rostering, hiring, planning, and the coordination a supervisor would otherwise own (Martela and Nandram, 2025). The span of control did not disappear. It was pushed inside the team and shared among peers. What looks from the outside like an absence of management is, up close, management distributed so widely that no single oversight role is needed.
Why the ratio holds here
None of this generalizes automatically, and the authors are careful to say so. The model works best where interdependence between teams is low, where frontline staff are highly motivated and competent, and where the service can be delivered in modular units (Martela and Nandram, 2025). Home nursing fits: a team can serve its patients largely without waiting on another team. Raise the interdependence, and coordination that peers could handle inside one team starts spilling across boundaries, which is exactly the work a middle manager used to broker.
This is the trap in copying the number without the conditions. A company that admires Buurtzorg's one-to-forty-five ratio and imposes it on tightly coupled, interdependent work will not get a flat organization. It will get overwhelmed employees and a coordination vacuum, which shows up as the complexity McKinsey found two-thirds of leaders already complaining about (McKinsey, 2023). The ratio is downstream of the design. Import the ratio alone and you import the risk without the structure that contains it.
There is a second subtlety worth naming. Buurtzorg's coaches serve dozens of teams precisely because the teams are small, capped at about 12 people, and self-contained (Martela and Nandram, 2025). Small units are easier to coordinate internally, which reduces how often a team needs to reach outside itself for help. The wide support ratio and the small team size are the same design decision viewed from two ends. A company that keeps large teams but tries to stretch the support ratio has misread the mechanism. The teams have to be small enough to self-govern before any single supporting person can serve many of them. Scale the team down and the span can scale up; leave the team large and the old span reasserts itself no matter what the org chart says.
Reading your own span
The practical move is to treat span of control as a diagnostic rather than a target. Deloitte found that managers already spend nearly 40 percent of their time firefighting and only 13 percent developing people (Deloitte, 2025). A large share of that firefighting is coordination between interdependent units, precisely the work that a wide, authority-free support ratio cannot absorb. If most of a manager's real value is brokering across boundaries, the organization has high interdependence, and Buurtzorg's arithmetic will not survive contact with it. If most of the value is coaching and the units are genuinely modular, a far wider span becomes plausible.
That is the strategy hiding inside the number. Flattening is not a decision to remove managers and hope the span stretches. It is a decision about how independent your units can be made, because independence is what sets the ratio, and the ratio is what determines how flat you can go. Ricardo Semler's version of this ran on the same logic: shrink the units, hand them real decision rights, and the supervisory span takes care of itself. Get the interdependence low enough and the middle manager becomes redundant. Leave it high and no span of control, however fashionable, will save you from needing one.
Sources
- Martela and Nandram (2025). Buurtzorg: scaling up an organization with hundreds of self-managing teams but no middle managers. Buurtzorg supports 900+ teams with 21 authority-free coaches (~1 per 45 teams) and teams capped near 12, and names low interdependence and motivated frontline staff as the boundary conditions. https://link.springer.com/article/10.1007/s41469-024-00184-y
- McKinsey (2023). The State of Organizations 2023. Two-thirds of leaders see their organizations as overly complex, the outcome of stretching span of control past what interdependence allows. https://www.mckinsey.com/capabilities/people-and-organizational-performance/our-insights/the-state-of-organizations-2023
- Deloitte (2025). 2025 Global Human Capital Trends. Managers spend ~40% firefighting and 13% developing people, evidence that coordination load, not headcount, sets the achievable span. https://www.deloitte.com/us/en/insights/topics/talent/human-capital-trends/2025.html