When I get a quilt back from my LAQ, I always trim the extra backing and batting and set aside. Then when I am bored but don't feel like sewing, I use my seam ripper to separate the two, save the backing for scrappy quilts and save any batting which I use for my lint sweeper/cleaner upper. The batting grabs threads, lint etc from machine area and also its good for dusting.
I use on my cutting mats and if rotary holder is linty I gently wipe it off with doubled batting. Batting is also good to mop up spilled liquids--scrap batting that is. Then you can just throw away-repurposing is cheap!
Jill M