There are several different routes to release a new feature to Wikimedia projects:
#1. Release as a beta feature (mw:Beta Features/Package has criteria for release and graduation)
#2. Release as an opt-in preference
#3. Release with an opt-out preference
#4. Release for logged-in vs anonymous
#5. Default release for everyone with no opt-out
Other?
It would be useful to have a recommendation about what type of release to use in which situation, documented in the Technical Collaboration Guidance.