2 battle ship > 20 Burst Fire?

I did not think torpedo was as useful as Cannon. It took like 6 hits at level 1. It's already a very slow skill and you're just wasting time when Cannon is a much 4 hits each.

So... 4 hits for 3 monsters is 12 hits. 6 hits is 6 hits for all 3 monsters. How exactly is Torpedo not as effective again? I don't follow your logic.