One must also consider the burner configuration and shape of the flame. Flame spilling around the bottom and up the sides is a sign of inefficiency. As a result a narrow pot will always be a poor match for a wide burner WRT efficiency but can be fine perfectly fine on a stove with a narrow flame.

That said, sometimes a tall, narrow pot fits one's needs better from a packability standpoint and a little efficiency loss is a fair tradeoff.

Cheers,