Why do companies often recognize the need for strategic change yet act only after critical windows have narrowed or closed? This paper argues that delayed strategic turns are not primarily the result of poor leadership, cognitive bias, or incentive failure, but a lifecycle-dependent outcome of organizational evolution. As firms grow from startup to scale-up, structures that improve efficiency—metrics, routines, governance layers, and strategic commitments—also reshape decision timing. External pressures become attenuated, internal signals increasingly filtered through established indicators, and corrective actions more costly to reverse. These dynamics raise decision thresholds precisely as the cost of delay accelerates. The paper develops a stage-based model distinguishing exploration, stabilization, and inflection regimes, showing how strategic inertia emerges predictably during growth rather than only at maturity. It introduces diagnostic indicators related to pressure transmission, signal integrity, and commitment irreversibility, and outlines governance interventions aimed at preserving responsiveness under scaling. The analysis reframes strategic inertia as a governance risk that can be detected and managed before performance deterioration becomes visible. ---Suggested citation:Huang, Q. (2026).Why Companies Turn Too Late: Strategic Inertia from Startup to Scale-UpZenodo. https://doi.org/10.5281/zenodo.18287053