Have you looked at doing a long term stable release that only gets fixes for bugs and security fixes, and keeping a monthly release for those who install for the first time and for those who always want the latest-greatest? This would be similar to the Ubuntu LTS method https://wiki.ubuntu.com/LTS and the Firefox ESR method https://www.mozilla.org/en-US/firefox/organizations/faq/.
What metrics do you have? How many orgs upgrade every release? For those who don't upgrade every release, how long do they stick with a back-level release? Do you have more new users for each release than existing users who upgrade?
For those who upgrade infrequently, what is the reason? Is upgrading difficult? Do they feel that their user base would be unsettled by monthly changes? Is their usage too low to justify a monthly upgrade hassle?