A lot of this is all dependant on the question

"what do I intend this first aid kit for"

There is a HUGE difference between a "after disaster" kit, a "trauma" kit, a workshop kit (even a home workshop) and the classic "Mom with kids" kit - LOTS of overlap, and the bigger kits will be able to handle the lesser stuff, but

The other question is - How far/long (distance way less important than TIME) are you from regular medical care?

Many times when I was younger, I was a GOOD 12-14 hours walk without injury to the first telephone, and there was no such thing as a cell phone. Get hurt back were we used to go, and you were going to have fun. We "what if'd" some really possible scenarios like a broken leg/arm, and which way we would decide to go to get out. The real issue was the shortest HEALTHY way out would require two good arms, or some what to get someone up a 15-16ft rock face - You had to toe walk on a 4 inch or so wide ledge that went up this face, and you NEEDED to hold on - NOT something I'd want to do with an injured person. The problem is, the OTHER way out, without packs/packs stripped was about 25% longer time wise, and a LOT further distance wise

Our general conclusion was "stablize, and send team to get people to help" - the shorter way (the way with the rock face and a few other scrambles) could have a ATV/SUV get about 75% of that 12 hour walk distance - that first 25% though would probably require a litter, and some rope work to get a person with a broken leg out

So, the first aid kit for that would have to be "You better figure on 3/4 day or better before you get outside aid" - way different than when I gashed open my finger last year, and it was' OK, let's control the bleeding till I can get driven to the hospital 15 minutes away" - (4 stiches later...)