I recently saw a video of a Kevin Evans' dog being worked on sheep. (I think the dog had been for sale, and this video was used to show the dog working.)
Among other things, he had the dog hold the pack of sheep (5 or 6 sheep) against him while he was backed up to a fence. He seemed to want the dog to hold them in a tight pack against the fence while he stood in the middle. Not for long, maybe 30 seconds, then he let the sheep go and the dog worked the sheep some more before repeating this exercise.
I am not fully understanding the purpose of this exercise. What is this teaching the dog? I have an idea or two why, but wanted to hear expert opinion.
Thanks for your input.