As of mid-2016, the Core team announced a new strategy for CivICRM development and release management: LExIM
Why a new development strategy?
The core team and partners are always trying to improve the reliability of the CiviCRM software while continuing to innovate and develop new features.
The development strategy used so far was based on a traditional software development cycle based on major releases for the main branch of the software, and a community-maintained Long Term Support (LTS) for people wanting a stable and reliable version of the software. While this model has worked very well over the past 4 years, it had the drawback of having less users test new features in the main branch (since running the LTS), and developers frustrated because new features had a very long time before being included in the LTS. Release dates were also unpredictable, causing scheduling issues with service providers.
What does LExIM stand for?
LExIM stands for Leap by Extensions & Iterate Monthly. It basically means that: