And she is not nearly quick enough to prevent the dog from running into a mistake. She needs to anticipate a fast dog and be there before the dog to prevent the dog from doing the wrong thing.
A long time ago after I bought my first Belgian I went to a dog show just to hang out. I encountered the breeder downstairs grooming her dogs. By then I had learned just how different my Belgian was from my German Shepherd. The dog taught me how to teach her. The dog taught me to always be sweet, to never correct, simply withhold praise and that crushed their little hearts. Even I was eager to get to the place where I could praise. And then do that moderately or else the dog will just freak the f out.
I asked the breeder if she would like to see what we learned together. The breeder said, "Yes, of course."
I ran the dog through the basic paces. Right there on the floor where everyone was grooming their dogs. Ordinary standard obedience.
The breeder said that my timing with the the dog is remarkable. The speed that I walk, the 3-step slow down way that I stop. My exceedingly gently handling. I'm just ahead of the dog. A very fast dog. Super eager to respond. Given to mistakes of anticipation. Just a half-step ahead so the dog is always working up to me and I'm always there to praise her. Extremely gently, a touch to the ear, a very soft calming comforting, "good girl." Soft suggesting commands.
So when I see trainers rude to their dogs it bugs me. They're little babies.