Mine very rarely ventures out of his "den" that he shares with a pistol shrimp. Very timid, and doesn't do much to sift the sand, other than immediately surrounding the entrances to their home. Lot's of major excavating, then you pretty much don't see him, except to poke his head out at feeding time. Mine is several years old now.

If you want a cool sand sifter, I have a twin spot goby that does a great job. They are supposed to be hard to keep, but if you have an established sand bed, they should be okay. Very visible fish - out much more than the yellow watchman. Always roaming and "chowing down" on the sand, but doesn't scatter it - filters it right back out through his gills. Very neat fish...