Y'know .... I didn't say or do anything different than you did. My comments were also based on 15+ years of dog training at a local community college. I usually offered one six-week class per period, open to ten students and their dogs. By popular demand, I always ended up teaching three groups...
"Easy," of course being a relative term. That dentist went to school for many years to learn how to do that extraction, and a dog trainer only makes it look easy, having studied and practiced and rejected many theories of training. Then they have to train the owner, who has to actually listen...
It is not so much a matter of time as it is a matter of KNOWLEDGE. If a person does not know how to train their dog, they need to put themselves in the hands of someone who does. Either get a good book on dog training like one from Richard A. Wolters or the Monks of New Skete, or hire a...
I think if you teach your dog Down, Stay, and he knows it properly, then he should hold it even if a chicken walks over the top of him. If he doesn't, then he isn't thoroughly trained. And I think any dog can learn it, regardless of breed, with the proper techniques. This is just my opinion, but...