I used garlic on the first and last lane but I never thought about about moving all zombies into one lane.
If you do that, you've got more chance of getting more zombies with a cherry bomb, which is one of the achievements. I've only got about three because I've not got that far into the game yet. The garlic was a tactic I used in the PC version.
Woohoo! I finally unlocked the Yeti zombie. Only one more Achievement to go and I'll have completed the whole game!