I have always, for myself and my kids, either done it at Passport Agency offices or at missions abroad. At PA's I have never waited more than a day (often same day) from abroad, it has never been longer than 8 days, and has been as few as 4 (which is impressive as the document is being made in the US shipped to the mission). I do not think I could be without my passport for more than 10 days or so (oh yeah, and I demonstrate that to the and is one of the reasons they let me have two!)