If memory serves, it is an hour. Still, when the team created the rules back when the new owners took over, we discussed this topic at great length. This is pretty much SOP for all forums for the exact reason you spelled out. I do, however, see value in allowing it in the Classified section, but I don't think you can make that specification with the software. Either way, it is still very easy to request a mod make an edit or a delete for you, or at least make the call on its necessity. That is what they are there for.
2000 Navigator 4200 Classic
(NOT a trawler)