Some problems from the lack of minerals (as if we don't already know!): low calving rate, fescue toxicity, grass tetany, hoof rot, cracked hooves, red hair, long hair, low fertility... The #1 mineral that cattle need is H2O. That might sound dumb but the most weight increase we ever saw was installing more and better sources of water. I have "lived" this mineral deal for decades. As we stepped from blocks (a general waste compared to returns) to cheap loose minerals to adding some supplements ourselves to going from learning to learning to learning - we are not with a custom mineral. We switch from Hi Mag now through Mother's Day and back on a summer mineral for the rest of the year. The custom mix is odd for some as we use chicken litter and that is high P. Minerals don't need to supply it. The ingredients that have cured a lot of ills: copper, zinc, iodine, selenium and maybe a few more but with above standard levels of these ingredients which are found in cheap minerals. And the source ingredients are not the economical cheapest to do the best.
This talk and babble about running cattle like "nature" is a smoke screen. Who checks the fawning rates of does and culls the ones that do not breed, have birth troubles... or culls every buck that is slow growing and thin muscled? Or how about culling for the hard-doing deer or the ones most susceptible to disease? This comparative is worn out and has no validity.
Regions and soils vary. Breeds vary. Expectations vary. One constant: blocks are a poor source of minerals in adequate amounts for daily needs. Another constant: tubs are expensive, whether protein, energy or mineral types. But they are convenient and I have used them judiciously when weaning or doing AI. I use them at those times for my advantage.
It's all about expectations. I want a calving season of less than 60 days. I want adequate growth and acceptable type, conformation and muscling in calves. You likely want something else and rightly so. But it takes decent, loose and proper minerals around here to make it happen here. I know that from 50+ years of seeing it all.