[forinti]

I think the objective is to show how strong you are. If you wanna go fast, use freestyle, if you want to conserve energy, use breaststroke or backstroke. I don't see a reason to use the butterfly outside of a butterfly competition.

[Contax]

In my case the reason is to exercise. I really like it as an exercise. Though I also practice the other strokes for more variety, and fun, when I'm short of time butterfly is my choice.