We have had a few discussions here about the "long down" (or power down as some people call it.) During the discussions, many people have poo-poo-ed examples of why you would need a long down in the "real world." Here is a personal example that happened yesterday.
On the way to the show, Riggs started yelling in his crate. When he starts that there is an serious "problem" on the way. I was on the highway with cars passing at 75-80 mph. There was no place to pull over, so I got my car as far out of the way as possible and waited for a break in the traffic to get out.
I then stood next to my car and waited for a chance to open the driver's side back door to get him out of his crate.
I leashed him as fast as I could and then called him into a heel to get him around the car as fast as possible. With no exaggeration, cars were about 6 feet from us, obviously had he decided to launch out of the car or charge to the end of the leash he could have been killed.
After he finished, I put him in a down to wait for another break in traffic. It was well over a minute before I could get back into the car. He was in a down on wet cinders in the rain. He didn't move or fuss, he just stayed where I put him. When there was a break in traffic I got around the car as fast as I could with him right next to me and then got him into the car and his crate.
I'm not trying to be dramatic, this is exactly what happened and why I think that a decent heel and down are essential to training. Yes, I stood on his leash as a safe guard, but he didn't fight me either. An instance like this could happen to anyone at any time (it was that or have a crate and dog covered with exactly what you are thinking).