I'm always amazed -- despite the fact that it happens every single day -- when parties file a petition for rehearing and rehearing en banc in circumstances in which there's no chance (not even one in ten thousand) of it getting granted. When any rational obersever would realize that, at best, the petition for rehearing will only cause the panel to slightly modify its opinion with nonsubstantive changes and that the petition for rehearing en banc will fail to garner even a single vote.
Like, today, here (with RJ Reynolds). And here (with Juan Rangel).
Wasted time, money and effort.