While going through Review: Low Quality posts, I find a lot of ones that I would recommend to delete, but another user has already recommended it to be deleted (I assume they did seeing that most of the time there is one of the pre-set comments linked to a reason there). What should I do if it is already addressed? Do no reason to not add another comment, add another comment, or skip it?
If you feel something should be deleted in the low quality queue, go ahead and hit "Recommend Deletion". If it already has a comment, what I typically do is select no reason, but if you select the same reason as has already been specified, it won't leave a redundant comment.
When a post hits 6 recommend deletion votes (and possibly with no "Looks OK" votes, I'm not certain about that condition), it is deleted.