You actually listen to those silly ATIS messages?? Just kidding.
I agree with SSDD, you would see this if they were landing runways that crossed each other. The notice on the ATIS gives you a heads up to be vigilant for traffic that may be coming from a different direction.
I'm sure it can be used anytime conditions warrant it (light to no wind, good viz) and/or a high load of traffic is coming in, and landings/takeoffs need to be expedited.
I did a brief search in the AIM for the exact defintion of it, but wasn't successful. Maybe someone else can back it up.