Sure seems like release is on somewhat of a whim to me.
Elven Blood, which contains CMPs 2011-04, 2012-05, -06, -07, and -08, was released for SR4A only on 2012-09-17.
Sprawl Wilds, which contains CMPs 2010-01, -02, -03, and -04, was released for SR4A/SR5 on 2013-07-11.
Firing Line, which contains CMPs 2010-05, -06, -07, and -08, was released for SR4A/SR5 on 2013-08-28.
London Falling, which contains CMPs 2012-01, -02, -03, and -04, was released for SR4A/SR5 this weekend.
All of the CMPs from 2011, with the exception of -04 which is contained in Elven Blood, along with all of the 2013 and 2014 CMPs are as of yet unreleased as far as I'm aware.
Additionally, SRM04-05 ("On A Silver Platter") contains a CMP2010-02 called Copycat Killer, which is different from the CMP2010-02 called Carbon Copy included in Sprawl Wilds.