KPIs should be modified when strategy, operating model, or material conditions change -not on a fixed calendar. Option D captures best practice: stable KPIs enable trend analysis and accountability, but rigidity can make KPIs irrelevant when priorities shift (new product, new market, regulatory changes, restructuring).
A key measurement challenge is over-modification: changing definitions or KPIs too frequently breaks comparability and invites gaming. The solution is governance: version control, documentation updates, and clear rules for when a KPI change is justified (e.g., objective changed, definition wrong, data source replaced, KPI no longer drives decisions). Many organizations review KPIs quarterly or annually, but that is a review cadence , not a mandate to modify. Most KPIs should remain stable, with changes treated as controlled exceptions. Strong KPI management balances continuity (to track improvement) with adaptability (to stay aligned). When KPIs are adjusted, communicate changes clearly and maintain historical mapping where possible so performance analysis remains credible.