Like Tom Wilson said, I too strive for high percentage of workers. I've had good success (and dogs that are excellent farm workers with little/no 'formal' training.
I've bought in dogs that were nice pets and could be useful on smaller places with little work for them but were better suited (IMO) as pets.
I strive in my breeding for 100% capable of being useful at the very least. I want a dog that can do a good job with livestock with little training (better yet, 'on the job' type of training.
Many years ago I sold a pup to a farmer. A few months later his neighbor called and wanted to know why my pup didn't need any training. He had bought several dogs from several people (some Open trail winners) and ALL his dogs had to go out for training. My reply-his neighbor was lucky.
Now I realize that a good dog is a result of good breeding but it does take knowledge and willingness to let the dog think and do a job to get the best. But I'd prefer a dog that can do it's job with little training and less handling