I have never had much trouble with slugs. I do see them, but do not see much damage caused by them.
I live at the edge of a marsh and each spring there is a large number of toads and frogs which hatch and move into my gardens. They are very effective predators against the slugs. I have a little over 400 hostas and really do not get much slug damage. Much more damage is caused by falling twigs and acorns. I have a couple of very large oak trees and when they produce a bumper crop of acorns it sounds like it is hailing on my roof on windy days,
I didn't realize that horseradish roots were a good defense against slugs. I put in one plant several years ago and now have several. It is upposedly marginally hardy here, but has done quite well. It is a weedy looking plant, but I actually like the large creamy white flower heads it produces,