This topic has been studied and discussed for many many years. My college thesis was titled " The Economics of Beef Cow Size to their Economic Performance". I did this thesis in 1972 or 42 years ago. There was volumes of research available back then, to read on this subject. Montana State University, Colorado State and several Southern universities and research facilities, had many studies on this. There was also several studies done in Canada, at Beef Research facilities, and the U of Alberta and Saskatchewan.
Probably the most significant research I got when I was writing this thesis, was directly from a man named Jerry Linton, from Chillicothe, Missouri. His Linton Charolais Ranch was one of the big players in the Charolais business at that time, and he was also a very prominent beef industry lobbyist. I decided to phone him one evening when I was writing this thesis, and he was gracious enough to send me a huge amount of data he had collected on his ranch. I am still a bit in awe, of this man, as after our first phone conversation, this very busy man would phone me on several occasions to see how I was doing on the paper and to discuss the topic. At the time, he had also entered politics and was running for Congress. Then his phone calls stopped, and I will always remember eventually phoning and his wife telling me that Jerry had been killed in a plane crash.
His research, like many others of that day, pretty well showed that the most economical cow size was dependent on a few factors, including the environment the cow was in, the management provided and to some extent the breed of the cow. Almost every study I found back then, came to the conclusion that the most efficient cow was somewhere in what we would call the moderate category. In almost all cases, too small or too big did not produce the best returns. It was the more moderate cow that usually came through. The only case I remember back then was a study in Alabama that used a set of Jersey X Hereford cows against straight Hereford cows and the smaller Jersey cross cows proved to be the most efficient. I could have told them that before they wasted a bunch of money to study this! In Alabama, the Jersey cross cows probably came through much better than they would have if they were studied in NE Wyoming on Mill Iron's place.
In the case of the Linton ranch, Jerry had done his own research for 15 years, and with his set of Charolais cows and his environmental conditions, the most economical cow was a cow that weighed 1425-1475 at weaning. He weighed all his cows the same day as he weaned the calves off of them. I remember him telling me, several times that his research did not mean that these were the cows that made him the most money, as most of his cattle were being sold as purebreds, and that oftentimes, purebred breeders did not pay much attention to economic performance ( ain't that the truth!!). He said that he was doing this research as he wanted to produce bulls that commercial producers could use, knowing that they had come from efficient mothers. I have oftentimes wondered where this herd, and this man would have ended up if he had not been killed. I have been told since then, that he had been noticed by many people much higher up the political ladder, and he was being groomed to eventually run for President. I am not sure if this has any truth in it, but I have been told this more than once.
The only other thing I would add is that many of the research papers I read, also made reference to the fact that it was important for purebred breeds to maintain some genetics both on the bigger and smaller sides of the equation, so that they could make the proper quick adjustments when they were required.
I fully expect that this topic will still be being discussed 40 years from now, and there will still be a wide array of opinions. I think the key is every person who wants to raise cattle, has to make the following decisions:
1) identify what your environment is like
2) identify how much management you are willing to provide
3) identify your target market( s)
Raising cattle is more than a lifestyle to most. For most of us, it is also a business and in order to maintain your business, you have to make money... at least some of the time. What works for you may be totally different from someone down the road from you... or in another part of the country. If you both manage to survive, then the lines between one being right and the other being wrong .,.... start to get a bit fuzzy.