Unfortunately, this is a point that I only discovered late in my knife nut life. In my younger day, I tried to cover ALL my bases and ended up lugging around more junk than I care to list. It didn't help that I was into the silly prepping trip and had lost sight of many of what my parents and grandparents had known decades before I was born. That you can't ever really be prepared for "everything" but with a few basics and some knowledge, you can be prepared for most, maybe even 98% of things.
On the subject of knives, my lesson came later in life after dad passed away, and just out of sentiment, I took to carry his little Case Peanut. I had always been of the thought that if I didn't have at least 3 inches of blade, I was under knifed. No, I was wrong. When I used that little peanut, it cut whatever I needed to cut with no problem. The same epiphany took place with SAKs. I watched my wife use and abuse a little SAK classic, and I thought it would fall apart under her use. I was wrong again. When I did my own experiment by carrying a classic on a trial run, I made it a point try the 58mm first, before I went for my Tinker or Wenger SI. To my huge surprise, it did opened boxes, mail, cut twine, broke down UPS and Fedex boxes for recycle, dealt with small flat and Phillips screws and actually let me fix things off someplace, and the scissors cut like the dickens.
I ended up convinced that all those years I had lugged around all that
'other' stuff, I had been wrong. None of it was needed. I had forget the lessons had learned from watching dad and a couple of uncles deal with stuff in their minimalistic way. In the 20 years I lugged around a Randall number 14 as my woods/camping/hiking knife, it was never needed. Being a Randall, it got sold for more than I paid for it.
It all really depends on who we are, what we are, and where we are. For most of us living urban or suburban surroundings, we really don't need much knife or tool. A small sharp blade for opening packages, a little screw driving capability, and maybe some small scissors to deal with a chipped nail, is most all we need. I figure if I go camping, I'llhave an appropriate fixed bade. If I go fishing, I'll have my fishing knife. If I need to deal with a can. I have my old P-38 in my wallet.
I'll settle for 98%!