Occasionally you will run into a drawer box that is out of spec with a cabinet and makes the slides bind a bit. I usually make my boxes 1 1/16" smaller than the opening so that if anything it is loose, being as tight requires much more work. Years ago because of my interest in old cars I came up with a great solution that is fast. In automotive bodywork there are these little shims to make fenders line up. They are U shaped with a little bent tab on the top. I buy the 1/16" size, and if you have a drawer that is binding because it is a touch narrow you just loosen the screws to the case and slip one of these in between the slide and the case, tighten the screw back up. Fast and they look like they belong there. If you need more than one they are stackable.
Carquest part # 8021634
Larry