For driving or walking? Likewise, I've had the wallet-sized ones to book-sized ones, and they end up getting used for all the band-aids and an ibuprofen packet, then kept around until the wipes dry out and the rest of the meds expire. At the moment, I have one of the Kroger brand first aid aisle things under my seat, mostly because I had no band-aids and decided all the wipes were dried out and meds expired in the last one I bought. All the department stores are on end of season, so it also should be easy to score as little or much of a bag of stuff as one wants at a discount from their outdoor sections right now.
My walking around for the day kit is usually just the duct tape around my lighter and cleanest article of clothing I'm wearing. On the rarest of occasions, I remember to pocket a couple of band-aids.
Benadryl did a friend's dog right when it got into a fish carcass full of wasps, but that was the last made-for-hiking first aid kit I had. The dog was uninvited from fishing trips after that, and I have an even stricter "your dog-your problem" policy now.
My go-to hemostatic agents are just pressure and elevation. I sealed up a cut too well with skin glue once, without it being as clean as I thought I had gotten it and ended up with a nasty infection as a result.
I don't mean to be flip or rude. Simply, whenever I've really needed a first aid kit, there wasn't one to be had, or it didn't have what I really needed, so I've used towels and duct tape to pressure pack an avulsed piece of meat on someone's leg, splinted a compound-fractured arm with the rolled-up, cardboard bottoms of reusable shopping bags and and a torn up t-shirt. Each time the victims found me to report the doctors were most blown away that a random stranger knew what to do well enough that the first aid had made a difference in treatment and healing rather than having been kind but ineffective or even making things worse.
Most recently I whacked a finger really well staying in a bunkhouse with two wilderness first responders. Insisting they were trained to take care of me, they foisted matching outdoorsy medical kits at me with a "stand back from yourself!" attitude as I was wrapping the cut in paper towel and the tape off my lighter. Neither had anything I could use, and I rocked black tape until it stayed closed on its own. Even they only kept these things on hand for the half inch by three inch band aids and emergency Midol, and they'd used them all up.
Point being maybe, more than having a good kit, just know how to apply first aid.