Django's philosophy on updates?
Possibly not a question for that site, but i will answer anyway.
Django does not have strict policy if you should update or not and if you can touch core files or not, it is totally up to you. But as always - touching core files is not good idea. Django core files usually lives outside of your project so there is no reason to change them.
Versioning of django is very simple: all major releases (1.6, 1.7, 1.8, 1.9, 2.0 etc) have some new features, all minor releases (1.8.2, 1.8.5 etc) have only security and bug fixes - so it will be totally safe and recommended to always update to newest minor release. There are some major releases marked as LTS - that releases will have security and bug fixes released longer than other.
And that's all. Rest of all is totally up to you.
With WordPress and other CMS out there, there is a philosophy that you should always keep it up to date, no matter what. And never change the core files. How does Django as a framework stand on this topic?