Trade and sell depo

I didn't know about the game system auto-buying unsold items in your trade depot.  Any idea on how long before it does that?  If you never bother to advertise the item, will it get bought anyways?

In much older versions of the game, it felt like certain items that were advertised after a while weren't being shown to other players.  I eventually listed a new item and the traffic from that sale brought buyers who also bought the stuff that was stuck.  I haven't put anything up for sale in a while so I'm not sure what it's like now.

Chris.