I don't really understand most first aid kits. I don't even carry band aids because they don't stick if you move or sweat. 95% of the time, all I've needed was a razor blade or safety pin to dig out a splinter, some Gorilla Tape to cover a blister, or some electrical tape and gauze to bandage up a cut. Add in ibuprofen for a good anti-inflammatory, acetaminophen to pull down a fever, diphenhydramine hydrochloride for allergic reactions or sleep aid, and aspirin for a headache or heart problems, and that's pretty much my kit. I also have all the basic personal toiletries, latex gloves, Neosporin, hydrocortisone cream, an ankle brace, super glue, nail clippers, tweezers, and eye drops. That has served me in every situation, whether enjoying the outdoors or doing construction. The times that kit has been insufficient were in the case of a scratched cornea, a cracked tooth, or major trauma.
I do carry a sewing kit for fixing clothes, but I hope it never comes down to having to repurpose that.