Done properly, it creates a small U in the line just below the rod tip. The motion makes the darter head tick, tick, tick across the bottom. The classic shake is a vertical approach that works best in deep water. A bow-mounted electric motor is a must, as pinpoint precision is required to fish vertically. If you mark fish on your electronics, keep the boat right over them and shake the jig in front of their snouts.
Few bass can resist that kind of temptation.
Classic shakin'also works well along ledges and steep rock faces. The swim is a horizontal darter presentation that's most effective when bass are suspended near structure or schooled in open water. This is common on lakes here where bass feed on smelt or other pelagic forage. Cast the jig out and gently swim it back with your rod tip, shaking the tip less frequently and sometimes not at all. A curly-tail worm is especially deadly in this situation.