[karmarepellent]

I have never seen a Debian system break due to auto-updates when they only subscribe to the common main, contrib and even non-free Debian repositories. They are incredibly stable and robust.

However one might want to use apt preferences/version pinning if they also use external non-debian repositories to e.g. install a newer version of PHP. Since some repositories keep different major versions in the same repository, an auto-update might otherwise install a version that causes an application to break.

That being said, most systems can probably get away with auto-updates and a little apt preference configuration and call it a day.