I've been putting my salt block at the same place for 8 years now. I put one of those great big salt blocks you get at a farmer's coop. They last for about 2 years. And they're much cheaper than the "specialty" deer salt... (I use the red colored salt block)

During the winter, the deer are yarding quite a distance from my spot and no tracks are visible in the snow in the general area where I hunt, EXCEPT for several tracks leading right to my salt block and turning back from where they came from once they got their salt. They travel a great distance just to lick the block, regularly. I guess my point is, once they know they have a source of salt in a particular area, they can count on it beeing there all the time, keeping them coming over and over, year round. Which is why you want to put a salt block in the first place.