The posts in this thread seem to suggest there is no training or certification by aircraft type for DL flight attendants. Is this true?

My only other reference point is SK back in the 90's. Their FAs attend a one-day orientation session, including a written test on the location of the safety equipment, before they are allowed to fly a new a/c type. In addition to this, even if an FA was certified to serve on several a/c types, their flight schedule on a given day could not involve more than one a/c type, in order to avoid FA confusion in the event of an emergency.