The icky shuffle is just a type of step for footwork drills. You are going to use the 1-2, 1-2 rhythm going back and forth over the line every time, while also rotating the basketball around your waist. The reason this is such a good basketball workout is because it causes the player to think while doing the workout, as well as adds difficulty to the drill by adding a basketball.
Along with adding difficulty to the drill, the basketball helps to also maximize time. The player will be able to work on their footwork and hands at the same time. Most footwork and agility workouts are only going to focus on footwork, but not this one. The player must push themselves and go as fast as they can through the workout.