The standard frontend testing strategy usually ends up being unit tests for complex logic and manual testing for the UI while hoping nothing breaks in production. It works okay until it doesn't. Every attempt to add E2E tests inevitably leads to frustration over how brittle they are. A single class name change or component refactor breaks the suite, meaning the tests that are supposed to provide confidence just create more maintenance work. At what point does E2E testing actually become worth the investment for a frontend team, or is there a specific codebase size where the tradeoff starts making sense?