It totally depends on how you want to test releases. You can have nightlies that deploy the latest green commit every day, do some QA there, then once it is feature complete promote it to a stable release that only cherry picks fixes, then finally promote it to production.
It will be highly dependent on the kind of software you are building. My team in particular deals with a project that cuts "feature complete" releases every 6 months or so, at that point only fixes are allowed for another month or so before launch, during this time feature development continues on main. Another project we have is not production critical, we only do automated nightlies and that's it.
> It totally depends on how you want to test releases.
For a big project, typically it involves deploying to a fully functioning QA environment so all functionality can be tested end to end, including interactions with all other systems internal to the enterprise and external. Eventually user acceptance testing and finally user training before going live.
It will be highly dependent on the kind of software you are building. My team in particular deals with a project that cuts "feature complete" releases every 6 months or so, at that point only fixes are allowed for another month or so before launch, during this time feature development continues on main. Another project we have is not production critical, we only do automated nightlies and that's it.