I think there are different kinds of effeciency. % calf weaned per cow weight. Effeciency in the feedlot on a high energy ration.....alot of times the big hard growing cattle do well here. Effeciency of a cow on a sawdust and sand diet..... can they survive, breed back, and wean a decent calf in a desert or even low input enviroment. I suppose if you wean a 10,000 $ calf off of a grade 1000 $ cow that would be a decent return. Fleshing ability=waste on a carcass in the feedlot so I think a balance is needed and current economic conditions will affect profitability and the type of cattle that work the best.