Last three jobs I've been at, we've had three environments. Staging - Continuous deployment; whenever code is checked into the main branch, it automatically go

Last three jobs I've been at, we've had three environments. Staging - Continuous deployment; whenever code is checked into the main branch, it automatically goes here QA - Once/twice a week we "cut" a release from what's in staging and promote it to QA. Our testers go through all of the changes and make sure that nothing is broken. We also have more rigorous integration tests running against this environment. Production - After everything is vetted in QA, it gets promoted again to production. I've seen some places have this take two weeks (in Agile terms, once a sprint). I've seen others do it basically every day (which IMO is too often). Once a week is the sweet spot for me.