I have had CPR/Self-aid/Buddy care many times while in the USAF. One day I finally had opportunity to use it at a car wreck. An old woman ejected from her car. There were 4 of us surrounding her, We each checked for carotid pulse. Some said yes, some said no. She was face down in a ditch. After a quick discussion we decided not to do anything due to risk of spinal injury and needing to roll her over and reposition her to do anything. The fire station was 1.5 miles up the road and we could hear them coming. In the end, she expired before they loaded her on the helicopter.
Paramedics told us we did fine considering the situation. It was not a fun situation to be in though...