[Callers] Telling couples to switch at the end of a contra set

Hey, I was wondering what other callers thought about the following: often, during the walkthrough of the 1st contra dance of the evening, the caller explains that dancers should trade places with their partner whenever they reach the end of the set However, I never do this, and have never had a problem as a result -- the experienced dancers in the set, apparently, are able to get the new dancers to do this, and nobody has ever complained to me that I didn't instruct dancers to switch I have wondered what others thought about this -- my own thinking is why take time to explain something when it isn't necessary? Regards, Mark Widmer / central NJ