How much should I kick when I swim?

Every coach hears this question. A lot! And everyone has their own ideas on the answer. I agree with Glenn Mills (GoSwim) on this one. Different kicks for swimmers and different swims. Just like you might choose different shoes for different purposes, swimmers could employ a variety of kicks. They could also have a very different kicking style when compared to other swimmers. What goes in to picking the right kicking style for a swimmer?