not always. my craw pattern'd cranks yes, but my bluegill and shad cranks I prefer to retrieve at what ever level the fish are suspended at. If you are in 20 feet of water, and the fish are suspended at 8-10, you dont want your crank digging into the bottom 10-12 feet below them, at least I dont. Now if the fish are on the bottom, dig the crank hard into the bottom or whatever else is down there
Okay, not ALWAYS...... but I have found if I'm not bumping the bottom a stop and go retrieve seems to trigger more strikes.
Basically your crank should have some erratic movement to it weather it be from contact with something or from yourself.