My daughter’s school had a race day to wrap up their swimming lessons, and one of the events involved rolling from front to back every second stroke. It was funny to watch but not very practical.

Sounds like burlap sack or 3-legged races. Completely impractical forms of locomotion, and irrelevant because that's not the point of the activity.

It is also my favorite, despite being the hardest due to the high skill required to do the proper technique. It is so awesome to feel so powerful.