See: https://www.mediawiki.org/wiki/Wikimedia_Release_Engineering_Team/Goals/201516Q2 (canonical for us)
gdoc version (Greg responsible for copy/pasting as appropriate) at: https://docs.google.com/presentation/d/1xXRP6kRsxsB-k8oXUHLY-FC7s2eOgkAO8T8isTnfYH0/edit#slide=id.g64646fd33_0_27