If you actually disconnect the terminals(unlike someone else suggested), and clean both the terminal and the post GOOD with a terminal brush(cheap, as Dana pointed out), then spray it with the anticorrosive red spray(the little rings they sell at the battery section help ALOT as well), it will actually last a while.
If you do that, it will probably be MONTHS before you have to do it again.
If you halfass it, you will probably have to do it every week. Its kind of like rust. Unless you totally get rid of it during the repair, it comes back 10 times as fast.