As to the question if I have ever stopped on a scene the answer is yes. My spouse is an experienced health care provider (read well beyond Medic & or floor nurse but not a MD either) and we stopped on a scene once several years ago, solo MC rider, no helmet vs guardrail and then pavement at 70+ mph. At the time we where the only other vehicle on the road and we stopped to assist. The pt had two full extremity amputations thanks to the guardrail, major closed head injury, and was generally hamburger head to toe. We called it in and did the best we could dealing with bleeding, and shock until help could arrive. We originally requested Air but it was not available due to weather conditions, 911 dispatch couldn't call for Air due to their protocols, so I called and got much further with Life-Flight direct until the closest crew declined due to weather and density altitude at our location. AHJ took almost 30 minutes to show with Fire and EMS and even then all they had were a couple of BLS providers. They wound up letting my spouse run PT care while I helped with PT packaging and loading, I followed the ambulance with my spouse in it 35+ miles to the communities Doc-In-A-Box(express sized at that) and then spent another three hours their while my spouse helped stabilize the patient so that the PT could get flown out. We learned that the PT did regain consciousness but died a few weeks later due to the head injury and massive infection due to the incident.