Different kits for different circumstances. I always carry at least a small, very basic kit,oriented toward trauma (one compression bandage and dressings, etc). If I am responsible for a large group, say on a field project of some sort, the kit is expanded; typically a SAM splint is in there somewhere (they make nice padding for the pack itself).

My SAR pack contained a stethoscope, BP cuff, pneumatic splint, and went on from there. There were occasions where the contents were exhausted completely.
Geezer in Chief