I used to live next to where a PD trained police dogs.I watched them daytime and night time.
It was a little mock up town type set up and yes you are correct NO was used often and is a very important if not the best to drill into this guys head.
HERE come in handy too
Single word commands only......I hate it when people talk in sentences to their barky little dogs that don’t pay attention to them anyway.
My dog trainer favored the word "front" to call the dog. In conjunction with saying "front" in a commanding voice, the handler would hold thhhhhir arm straight out to the side and then snap it to his/her chest with a closed fist. The dog was expected to bolt forward and stop at the handler's feet in a sit waiting for the next command.
The next command was "finish" which involved the dog circling the handler's feet once and sitting again -- this time facing forward.
In my dog's case (Golden Retriever) he would sometimes wander a bit instead of coming right to me. I solved that with the use of a special ball which he was never allowed to have on other occasions. Instead of my closed fist, I held a ball and thumped my chest with it. He was then allowed to have it for just a minute, and then I'd take it away from him, praising him all the way.
He never wandered again, even when I wasn't using the ball. The reason he couldn't have the ball (one that he'd found himself) was that it was a squishy, foam type ball -- not one that I wanted him to chew because he would have shredded it in minutes. But, he really wanted that ball. He would do anything if I showed him that particular ball.
My dog trainer wass paranoid about dogs chasing deer and wanted them to stop on command. She recommended the use of a shock collar. I really did not like the effect that had on my gentle Golden, but I used to wear a flash drive on a cord around my neck. I found that I could get my Golden to stop whatever he was doing by raising the flash drive like you would raise a cross to a vampire and sternly saying "leave it" or "stop".