When a file changes on disk outside of my text editor it's nearly always because I:

modified it in another editor, or

used git to switch branches.

(global-auto-revert-mode 1)

~/.emacs

In both of these cases I would like my editor to notice the change and start showing the new version unless I have unsaved changes. I can make emacs always do this by putting:in my. I've not found a situation where this makes emacs do something other than what I would want it to do.