As for mineral sites not helping the deer as far as antler growth and overall deer health, that is subject for discussion. A state biologist explained it to me like this. Dumping out a 20# bucket of commercial deer mineral works as an attractant, but most likely doesn't do a lot to promote a healthier deer herd...but, if you have a mineral site (his suggestion was one mineral site per 40-50 acres) and it contains the "proper" amounts of minerals (such as the mixture that TJ is using) it can definitely be beneficial to both bucks and lactating does. I have read the studies as well and while they show no proof that they mineral sites help, they also show no proof that they do not help. The biologist that I spoke with felt that the mineral site should start with 50# in late February to mid March and an additional 50# should be added 2-4 months later, depending on the amount of use the site was receiving. In other words, most mineral sites don't contain enough minerals to be beneficial.
The demand for the mineral definitely decreases in late summer/early fall. I kept a site going with a camera on a "no hunting" property a couple of years ago just to see what kind of activity the site got through out the year. March through July saw daily use, with the heaviest use March through May/early June. From August on, usage dropped off considerably, with October through January showing almost no activity.
Many, not all, of the commercial mixes are little more than salt and apple flavored powder and do not contain the necessary amounts of calcium, selenium, zinc, manganese and other things I can't remeber right now. Salt is a necessary part of the deer's intake, but they need more than just salt. Ideally, they would get the minerals they need from the plants (both natural and agricultural), but in many instances that is not the case. The mix mentioned is what is used by farmers and ranchers for livestock, so there must be some benefit in using it.
The same thought goes along with food plots as well. Guys will spend a bunch of money on seed for their plots, but little to nothing on the fertilizer the plot crop needs to thrive and provide the minerals the deer need. Put in 2 plots of clover and properly fertilize one plot and leave the other one alone...guess which one gets hammered?
If nothing else, it's fun to see what deer are using the property and see the changes in the deer from year to year!