Hikermor, you are spot on (as usual). Training and experience with the environment and circumstances are far more valuable than what you carry. Planning and knowledge of what you will likely be facing is also very critical. What is the most likely problem you will face, what is the most serious? You must prepare for both, but you can't always fit that in your pocket. As with survival, your brain is your most valuable tool, and it must be prepared just as you prepare with equipment and supplies.

Communications may be the most important thing you have, an ambulance has more supplies and ability than you can carry as an individual.

In my experience, the most common problems I have faced are hyperthermia or hypothermia. Those are actually easy to prevent and prepare for.

To Les, for range days I carry a significant trauma kit, just in case. Thank God I have never had to use it during range training, here in the US anyway. Prepare for the worst, hope for the best.

Without getting into a very controversial subject, it does appear to be necessary to prepare youths for penetrating trauma. I provide them with tourniquet, compressed gauze, triangular bandage; along with the basic skills in how to use them. The training they receive includes stopping bleeding, treating for shock, the basic recovery position to help avoid problems with the airway, CPR. I teach them to work in buddy teams when using these techniques as a tourniquet will cause pain (even though it will save a life) and the individual will usually try to take it off. They can also keep the person under control and observation, and move them if necessary.

I also have provided some with this: Door Block

I have tested it on various doors and it works pretty well.