It is a long held practice for a person responding to a medical emergency to use the injured person's IFAK to render aid to them.
This prevents their own IFAK from being utilized in case the threat remains and it may still be needed.
For this purpose, your IFAK should contain everything you can self-administer, as well as what can be administered to you if you are unable.
Take an example of a concealed carrier responding to an active shooter. The concealed carrier receives an injury, but a bystander is medically trained. The bystander has no equipment, since they didn't anticipate needing it. But the concealed carrier has the equipment needed. They may have just saved their own life by having that equipment ready for another to use.
Do you disagree with this practice?
I do not disagree, you are correct in that obviously if you are unable to render aid to yourself that your own ifak would be used on you instead of another’s, that’s the whole purpose they serve.
I do however believe that in almost all scenarios, a bystander in an active shooting that receives an injury is unlikely to have someone nearby who correctly knows how to use some of the medical equipment, and any medic you ask will typically not render a chest dart or NPA to an individual they are not familiar with for liability reasons. In cases like an active shooter there will typically be an EMS response fast enough to not warrant a NCD or NPA, therefore i believe that the recovery position is best practice in this situation as well as initial hemorrhage control for the GSW or whatever.
The unfortunate truth in a active shooter situation is if you have a patient who has an airway obstruction, and injuries severe enough they cannot be moved into a recovery position, and at the point they need a chest dart before they can get to the proper care, they are likely going to die.
To answer your question about carrying items another medic may be able to use, I do not recommend carrying anything in your medical kit in any circumstance that you are not trained in the proper use of. The only exception I see is if you know a person or people on your team are trained in their use and it would be reasonable to believe they would be the ones rendering your aid.
For an active shooter kit I would be carrying as many TQ’s as i could, as well as compressed/hemostatic gauze, and chest seals. This is a type of kit you can carry and forget, doesn’t take up as much room as full medical kit.
Now if you are trained in the use of NPA’s and NCD’s and are comfortable with the use of them and comfortable with the idea that the person you are trying to save very well might sue you, then they should be carried in an aid bag in addition to normal kit.