Those are good questions, but I don't know the answers. The photos and their captions are the entirety of the information I received. Given the massive size of the piles, it's hard to imagine their breaking them down too frequently. The close-up of a pile's temp chart records 3 weeks of data for that pile. While I would guess that the duration of a single pile is based on the internal pile temp (perhaps when it starts to fall), we can assume it's no shorter than 3 weeks.