In may I have been asked about Firefox deployment in enterprise environment but I did not know much at the time. Time for a first draft of what I’ve discovered so far.
Firefox has two variants, Rapid Release and Extended Support Release aka RR and ESR, both for enterprise environment.
Released every 6 weeks, just like Firefox for everyone but bugfixes are not backported to previous versions; make tests, fix your environment, move on. Here you can find the release calendar for RR
A softer approach is the Extended Support Release, just like a Ubuntu LTS edition.
Extended Support Release
Released every 42 weeks, follows the standard versioning so there is a jump of 7 Rapid Release between every ESR release.
Up to now we had the following versions: 10, 17, 24, 31 and 38.
Every ESR version has a support window of 54 weeks, an overlap of 12 weeks between the old and the new version gives you a lot of time to make changes and to be sure you can switch to a newer release without problems.
Sure, 12 weeks are a lot of time but you can get 6 more if you try the RR beta before the next ESR gets published, 18 weeks seems a lot better.
Again, ESR gets bugfixes for 54 weeks but after that it’s done, expect no more and switch to the newer version.