Call me foolish, but about all I ever take is Advil type stuff and sometimes a few items for blisters, which never seem to work if needed. If I think of it, I take a few band aids, and Percoset if I have any, but not usually.
I'm all for first aid kits and I think they're a good idea. But on the other hand, minor medical problems can be temporarily ignored, and the rare, serious problems probably need more than the odd pill or ointment.
Though I've done loads of backpacking, almost never more than 2-3 days from nearest trailhead, and usually a matter of a few hours.
I'd re-think this first-aid stuff for expedition-type travel.
Apart from a few cuts and scrapes and minor altitude sickness, the "medical situations" I've encountered have been limited to finding a drowning victim some while after the fact, a back-country skier with a broken back, a companion with a sprained ankle and me with a messed up knee.
I walked out over several days. The rest were evacuations.
I took a 20-hour "wilderness first aid" class 30 years ago, which fortunately hasn't proven useful, and I also did a CPR class about twelve years ago.