Reply to DJM-900 - Effect CF A/B assign, what do you use this for?

I was messing about on the DJM-900, and I see you can assign the effects unit to 1-4, and the Master, which I fully understand, but you can also assign it to the CF A/B...

Is there a specific use case for this?

If you were using the CF, you could just assign the effect to source you wanted. The only thing I'm believeing is you could assign it to say "B", and then have multiple channels assigned to "B" playing simultaneously.

Is there some other trick I'm not believeing of?