Flagging a comment is pretty low-effort. Handling flags probably isn't (as much). So it would be useful to have a guideline or two to know when to leave things alone because a flag would be "too minor".
Specifically, I ran into this when I saw a comment that was technically "obsolete", but I was wondering about whether...
- age of the question;
- the question was recently active;
- the number of views of the question;
- Misc. effects of the comment (e.g. whether it pushes a more meaningful comment into the "...click for more" section)
...should affect my flagging the comment or not.
Note that I'm happy to flag whenever technically appropriate, I just don't want to make our moderators' lives miserable :D
The closest Meta thread I could find were the flag decline reasons, but that didn't provide me with an answer to this question.
PS. What may also help is to know how the flag tools work or what they look like, and how they compare to the review queues (and the volume of tasks there).