I think it's important to point out that "throwing" it in reverse and just mashing the gas is not what is being discussed here. I don't want anyone to get the wrong idea from the thread title. I learned to drive on the ice filled mountain roads of the Catskill Mountains. Even our driveway was long, steep, rutted and gravel.
Keeping the rear of the truck behind the front of the truck was my sole purpose during the SNR. Only once did I get slightly sideways and was able to come to a stop. On some of the other steep downhill sections getting sideways would have most likely ended in a rollover. I used reverse, brake, gas, e-brake and "Jebus take the wheel" to get down. The one thing we had going for us was the trail is dug out a lot and shaped like a luge hill, as long as you just banged the sides and didn't go out of the "bowl", you could essentially just careen off the sides until you regained control.
Being last in the line of 12 meant there was no more fresh snow to "grab" traction on. It had already been spun/slid on and turned to ice. Here is a bad picture from earlier this summer where I was climbing the area that we descended that night. I would consider this a wide spot in the trail.