How much of an expert one needs to be depends on a number of factors, age of cattle being fattened to kill, breed and type, size of land base being managed relative to number of stock being run, species of forage you are managing, length of growing season, quality of forage after freeze up etc,etc.
One thing for sure though if you or whoever is handling the animals at the processors doesn't know what they are doing they can undo all the best management that went into getting the animal ready to kill.
Killing a fat open 2 or open 3 off of native grass in our country even in a dry year and getting an excellent eating beef does not take a heap of skill or expertise from my experience.
Making money on that carcass and making a successful business of it on a bunch of animals, now that is a different story.