There is actually bugger all point in removing snails/slugs from one's garden, as they are just part of a larger local population, that will replace the removed specimens more or less immediately. Or quickly, for a legless mollusc, at any rate.
I keep finding them in the middle of the street when its rained, and have to pick the little buggers up and move them somewhere they are not in the path of a crunching boot or car tyre.