The problem with Safeguard in the mineral is ensuring that they get the correct dose. It can be hit or miss.
Studies (fecals) done on treating with pour-on Ivomec products showed 50% effective. With deworming in the mineral there is some protocol. Having them on a mineral program, taking that mineral away for a couple of days, putting out plenty of mineral feeders, puttting no other mineral out until it is cleaned up, then going back and doing fecals has shown 95% of the cattle were clean. So you can treat them all with a pour-on and get 50% of the worms, or put the mineral out and get 95% of them.
Dr. Don Bliss, parasiteologist, has said deworming orally is best and over several days, as what happens when using mineral with Safeguard. I have sat in at several of his meetings. I do believe he is one of the first to come out with studies showing cattle resistance to Ivomec products. Here is a link to his Mid America Labs Ag research.
Strategic deworming, in our area means 45 days after turn out, putting out Safeguard in the mineral (yes, it is available already mixed) deworms cows and calves and cleans up pastures. We have had many customers do that, then run fecals in the fall and the cattle are clean going into winter. So they don't need to deworm again at that time. When Ivomec was real expensive, this saved the producers money. The calves were heavier, too. Of course a pour on was needed for lice and grubs but a cheaper product could be used.