....Once you get the training you won't need to ask the question.
I don't agree with this sentiment. My Father, who is a doctor, always brings far too much medical stuff with him on any kind of trip. Once on a family vacation, I got a small cut. My father found stitches, but couldn't find any band-aides. This forum is about packing light. The FAK is the trickiest part of this because typically you don't use anything in your FAK. The standard advice is to sit down after a trip and think about eliminating anything you didn't use on the trip... but we shouldn't do that with the FAK!
What are items people have thought about eliminating, but at then later found absolutely indispensable? I have a cold pack in my FAK. I'm definitely thinking about taking it out, but it could be pretty handy for a strain or sprain. What do others think? I've been thinking about adding benydril, but I've never needed it in my life.