It's easy to get too "technical." Anyone that has a herd of cattle should be able to visually look at the cows and figure out which ones are doing a good job and which ones aren't. Cull the bad ones, and keep the rest. Don't get bogged down with dinky details. If a cow has a pretty fair calf, and if she is pregnant and has all of her teeth, she is probably worth keeping for another year. Buy the best bulls you can afford to buy, but don't get carried away. If a bull that you like is getting too expensive, let someone else have it. There are lots of fishies in the pond, so to speak, and there are always other quite adequate bulls to be had. Biggest is not necessarily best, but don't go for small frame size, either. It is very hard to go wrong just staying in the middle of the road.
Uniformity doesn't mean much for taste, or matter much if you operate from conception to consumption. Uniformity, however, does matter a great deal if you market feeder cattle. Stay with breeds that are saleable. Often some offbreed critter works well on an individual basis, but gets knocked badly in a bunch.
Disposition is important, and quiet cattle are worth more to both ranchers and feeders. If your cowboys are too wild, cull them. There are always good quiet hands looking for work.
"Moderation in all things" is a good rule to go by, but other than that try to stay away from too many rules. Be adaptable, and be ready to roll with the punches. Each day brings new and different challenges. With that, I will get off my soapweedy box. :wink: