I actually used it in a few places, but oddly never in dungeons. I used it while running around Hyrule Field as a child when there were a lot of Stalchildren, in the areas where you would get swarmed by Guays flying at you, and also near the place where you get it with a swarm of Leevers when trying to get the big purple one to appear. Basically, I found that it was more useful as an overworld spell because swarms of weaker enemies were more common in the overworld, and wasting magic while you're outside of a dungeon running around looking for Heart Pieces and Gold Skulltulas isn't as big a deal as it is when you're in a dungeon and need to conserve magic.
The only time I can think of where I used it in a dungeon was after a Like-Like ate my shield, and I was up against a tough enemy with no other way to defend myself. I just wanted to get it over with and didn't feel like going back to get another shield, especially since the Like-Like was likely to come back if I left the dungeon anyway.