For repeated crosscuts using a miter saw or a crosscut sled or a radial arm saw, nothing beats a stop of some sort for consistent results. Same thing for some operations on a drill press with a fence. Problem is, setting the stop can be kind of tedious sometimes. You make a test cut, bump the stop a smidge, make another test cut, bump the stop half a smidge the other way, and so on.For the price of a drywall screw, though, you can set up a poor man's microadjuster that will eliminate most of the fussing. Just drive the screw into your stop and use it to register the workpiece instead of the stop itself. You can then make fine adjustments to your setup simply by turning the screw. A secondary benefit is that sawdust won't get trapped between the workpiece and the stop like it might if the screw wasn't there.Drywall screws work especially well for this, for a couple of reasons. First, they're not tapered, which means that they won't become loose in the hole when you back them partway out. Second, some of them have exactly eight threads per inch. That means that one turn will conveniently move the screw 1/8", a half turn will move it 1/16", and so on.