Applying a tourniquet to the neck would be officially frowned upon <img src="images/graemlins/mad.gif" alt="" /> though in some cases, it might be secretly applauded <img src="images/graemlins/grin.gif" alt="" />

I had one applied for surgery due to a severed tendon <img src="images/graemlins/frown.gif" alt="" />. The doctor applied it for about an hour to minimize blood loss and to have good sight. He stated that it was close to the maximum time they would leave it applied. Note that this was done in an operation room and not stop the primary bleeding (the cut was shallow and only 1/2 " long and stopped bleeding by itself).
I know some paramedics and emergency doctors. None of them applied a tourniquet on an accident scene.

When I was still riding as a third leg on the ambulance we got called to a subway station when guy had a leg amputated by a train. My first reaction was to put one on but older medic told me that they usually don't to it to clean cuts like that. And to my surprise bleeding wasn't that bad. But a month later we got called to a car accident where gentleman was having his forearm amputated. Since it wasn't a clean cut he was bleeding a lot and when part of the crew worked on spine mobilization I tried to stop the bleeding but all I could to is use pressure points since I couldn’t elevate the arm because that would compromise the spine. I was still under supervision of older guys and I really shouldn't be performing any procedures but they were short handed so I was told to apply a tourniquet. It stopped the bleeding to a slow trickle and than with every turn it was less and less blood. His hand with forearm was placed on ice wrapped and we did rapid evac. But I always have questions about stuff and procedures so I asked about application and placement. I was told that since there was a spine compromise and possibility for internal injuries and bleeding and there was no time for playing around. Older guys told me that they are trying to avoid tourniquets as much as possible.

Matt