A coach or infield leader will yell double cut.  Double cuts are needed when a ball is hit to the fence and there is gonna be a long throw to a base.  On a ball hit into the right field gap and the expected play is at 3rd base, the 2B will be the lead relay guy and the SS will be the trail man.  Then pitcher will back up 3rd base and 1B will trail the runner to 2nd base and then be the coverage at 2nd.