I think the length staying put thing has a lot to do with the shape of your shoulders, because mine always falls forward and has always fallen forward, and falls off my shoulders if I drape it there, but I know that a lot of other people can wear their hair as a scarf and it'll stay put. And I detangle once a day if I'm feeling especially diligent (and have damage-resistant hair), so that's obviously not the only reason.
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