> When I'm arranging my photographs in folders, I prefer yyyy-mm-dd. That way it stays in chronological order.

It is kind of interesting to think about that from a usability perspective, because the "stays in chronological order" refers to how most file system browsers default to sorting things by name. If it was a concious decision to sort by name, then the description would be something more like, "when I am sorting my folders by name, I'd rather sort by date, so I put the date in the name."

Folders do tend to have Date Created metadata, so in theory you could "sort folders by created date" rather than by name, but where that data is stored and how that data changes as the files are moved around is pretty opaque, so it makes lots of sense to not rely on it.