There is currently a 5-minute grace period on edits on questions and answers where editing it does not cause a new revision in the history.
I'd appreciate a similar grace period on comments, perhaps 30 seconds or so. Call me clumsy but I'll very often notice a tiny slip or unclear wording I want to correct immediately after posting a comment, but even if an edit is done within 10 seconds it still incurs the penalty of having the pencil icon stuck next to it.
This doesn't seem like the best use of the pencil icon, because when a comment is that new it's probably been scarcely seen in its original form and the edit is not likely to lead to abuse that would cause things to be read out of context (no more so than deleting a comment, anyway). The pencil icon would be more meaningful if it was reserved for non-immediate changes.
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I don't see the number...?