As defined by the FAQ on editing:
Edits are expected to be substantial and to leave the post better than you found it. Common reasons for edits include:
- To fix grammar and spelling mistakes
- To clarify the meaning of the post (without changing that meaning)
- To include additional information only found in comments, so all of the information relevant to the post is contained in one place
- To correct minor mistakes or add updates as the post ages
- To add related resources or hyperlinks
Many a user has had a perfectly valid edit rejected for being too minor. However, I came across this earlier:
It was edited in by a user with editing privileges who are expected to know and thus abide by the rules without requiring the review queue. I'd argue that it's not substantive and also does not fill any of the other criteria.
In an effort to improve my own use of the site I've been looking for a consensus on this, but there isn't one. There's a meta.SO question about minor edits in which Jeff Atwood says they should be rejected with extreme prejudice, but the highest upvoted answer on the question says they should be fine.
Personally I wouldn't have made that edit, because of the minorness of it, and I don't think it fulfills the criteria of editing. But someone else clearly saw this differently to me.
Should I go for an if-in-doubt-edit approach, rather than a more conservative only-edit-when-criteria-are-filled approach?