Does end-to-end testing unlock more value than just catching UI-level bugs?

End-to-end workflows are traditionally associated with validating complete user journeys — login, checkout, payments, onboarding. But effective end-to-end testing has broader benefits that directly influence developer productivity. Fast, automated E2E runs give developers immediate clarity about whether a change affects critical business flows, reducing the need for manual exploratory checks. This tight feedback loop shortens the time spent investigating regressions, especially in large applications with many moving parts.

Teams also use E2E tests to validate assumptions about user experience, helping developers align more closely with product goals. And when these tests run inside CI/CD pipelines, they serve as a powerful safety net that encourages bold improvements — developers are more willing to clean up legacy code or optimize performance when they know user journeys are fully guarded.

This brings up an important question: should E2E testing be treated only as a final validation step, or as a developer-focused tool that enables faster, more confident iteration?