How do teams implement effective End to End Testing in modern applications?

I am currently learning more about end to end testing and how development teams implement it effectively in modern software systems. Since applications today rely on multiple components like frontend interfaces, APIs, databases, and external services, validating the complete workflow seems very important.

I would like to understand how teams design reliable end to end test scenarios that simulate real user behavior. How do you handle challenges like slow test execution, environment dependencies, and maintaining tests when the application changes frequently?

Also, what tools or automation strategies do you recommend for running end to end tests in CI or CD pipelines?

Any suggestions, experiences, or best practices would be greatly appreciated