Moving forward the aim is for Ubuntu kernel updates to be done on a 4-week update cycle while having a follow-on release at the 2-week midpoint to provide any critical/high CVE fixes or any other critical fixes. In effect, a kernel update every two weeks but that mid-point release will be reserved just for more urgent items that can’t wait until the next 4-week release.

Original Announcement: https://discourse.ubuntu.com/t/ubuntu-kernel-4-2-sru-cycle-announcement/37478