This idyllic view sounds theoretical to me. What I've seen working best is a fast CI/CD pipeline with unit tests, key journey tests, and integration tests with

This idyllic view sounds theoretical to me. What I've seen working best is a fast CI/CD pipeline with unit tests, key journey tests, and integration tests with blue/green deployments. This in my experience is far superior to staging environments for both startup and very large scales. In addition the development environment itself should be as close to prod as is practical so most checks can be done there.