I've been using trace mineral salt block recently and they seem to use them most in the spring through fall. But it would be a good idea to keep them out all year round. Even though they may not use them as much at certain times they still use them and can rely on them being in that spot. I have been using them lately and the deer love them. I started with the regular salt block and they loved it and then started using the trace blocks and they love them just as much. I have even buried them in the winter during prime time and they have literally dug them up to get to it. Even though it does not have the vitamins and nutrients other blocks have it is a Great way to keep them in areas you hunt and very inexpensive compared to other blocks while including minerals such as calcium for growing deer.