End-to-end (e2e) testing is critical for identifying issues that emerge only when testing an entire system, but it is more complex, time-consuming, and expensive than lower-level tests. To optimize e2e testing, it's important to prioritize tests based on customer impact and automate where possible, while avoiding duplicating tests that can be conducted at lower levels. Utilizing cloud infrastructure and tools like LambdaTest can enhance efficiency by facilitating cross-browser testing and visual regression checks. Integrating e2e tests into CI/CD pipelines and using detailed reporting tools can provide valuable feedback and alert teams to potential issues, thus maintaining customer satisfaction. Effective e2e testing involves collaboration with stakeholders and experts to ensure coverage of critical user journeys, managing test environments, and maintaining organized, manageable tests to prevent unnecessary complexity and resource use.