RE: do salt blocks work well?
Yes ... but as others mentioned make sure that it is legal. Some states do not allow any minerals to be out during the season. Some, like Alabama, restrict the formulation of the minerals. Here is can be only NaCl. Every other mineral mix is illegal .. including commercial stuff like Come Mere Deer, Deer Cocaine, Stump Licker and molasses blocks, trace mineral salt, and such used for cattle mineral supplementation.
When the deer find the stuff, they will rip up the ground where a NaCl block, pelletized NaCl and/or granulated NaCl have been used to make a "lick". Get it out now and keep it refurbished as the stuff is being dug up.
Granulated salt here is about $6.00/50#.