Remember that 1 Cob setup that I used? I'm working on the 2 Cob timings for it suggested by Hitoridakeno, but at flags 54-56, Gigas smashed their way through both Fumes on the bottom row (despite the fact that they'd already been hit by one instant), they had earlier (I'm sure this is unrelated) smashed one of my Inner Row Glooms, I think one of my Pumpkins was completely eaten by Imps (I managed to replace it before it became a problem, luckily), but the biggest problem was the fact that my Cattails missed a Balloon Zombie, triggering one of my Lawn Mowers!
Note the missing Lawn Mower. The next flag without Gigas (which happened to be the next flag with Balloon Zombies), I rearranged my lawn a little. Here's what I came up with. The Cattails should be able to snipe down all Balloon Zombies now.
I'm now to 74 Flags! Here's the screenie to prove it: