A new feature implemented today and landed on mozilla-central can be delivered to our users in 12 to 18 weeks, not months or years. Mozilla has been living rapid release for a few months now, but weve been moving faster. The same process that gives us agility is giving us greater robustness, too. Testing and stabilization of each release across progressively larger audiences helps us find and fix bugs early, and build confidence in the quality of each new release. Were studying the effects of the process carefully to understand how rapid release can fit into software deployment systems.”]
Source: https://blog.mozilla.org/futurereleases/2011/07/19/every-six-weeks/