An incumbent technology improves fastest just after a substitute appears.
Gilfillan's observation from sailing ships, which improved more in the fifty years after steam appeared than in the previous three centuries. Competition concentrates effort that complacency had dispersed.
In practice
- A high street bank's branch service improves markedly in the decade its customers are leaving for the app.
- A print newspaper's design, photography and editing reached their best decade after the web had taken its readers.