0–39: Low maturity
On these answers the board is a ratification body: decisions arrive settled, packs are built to reassure, and dissent has a price. The danger is not daily (management may be competent) but conditional: when management is wrong about something large, nothing in this system will catch it.
40–59: Developing maturity
The forms of governance are present and the substance is intermittent: challenge happens on safe topics, risk is tracked but not confronted, and follow-through depends on individual directors' memories. The board adds value at the edges of decisions and misses the centre.
60–79: Moderate maturity
This board does real work: decisions arrive open, challenge is survivable, and commitments are tracked. The remaining vulnerability is homogeneity of input: a capable board hearing one well-prepared version of reality will make confident, aligned, occasionally wrong calls, and its own competence makes the wrongness harder to spot.
80–100: Stronger maturity
These answers describe a board that governs rather than attends: open decisions, honest papers, institutional challenge, tracked follow-through. What no internal practice can fully protect against is collective conviction: a strong board that has agreed on the world can be wrong about it together, at scale.