My theory on salt blocks is that deer will use them but not go crazy over them like they would a ripe soybean field or pile of sweet corn. I doubt deer head out of their way to find them. Or spend a lot of time around them. I'd use them as a supplement to the deer's diet and place them along trails you think they use. As for putting them on public land, if its well hunted, it will definitely be a tip off to other hunters you might have a good spot. Just my 2 cents.