In this particular case, it's been posted only three times this year, and the first two had only 2 or 3 points, meaning that hardly anyone saw them--I know I didn't. I wouldn't have learned about this if not for the repost.

I don't see anything wrong with reposting perennially useful stuff at reasonable intervals. Maybe twice in as many months is too much in general, but it seems to have worked out all right.