Only one of the knives I carry is unnecessary. I carry a small Boker KeyCom clipped to my right pocket, which also serves as a pocket dangler for a small Fenix E-15 flashlight. With that combo, I always have both a knife and a flashlight immediately available. The Boker is a very small knife but with the flashlight also serving as a lanyard, it becomes very easy to operate one-handed and has a very versatile clip blade. The AUS-8 blade takes a shaving edge and touches up easily by just stropping on a magazine cover. This is my "quickly cut open a box or bag" knife.
However, the KeyCom is too small for food prep tasks like slicing up an apple, plus it gets gummed up sometimes from packing tape until I take the time to clean it off. So I keep a Case Slimline Trapper (stainless steel) in my work bag, which is reserved for food prep tasks. Long thin blade, perfect for slicing food, easy to wash and rinse off without worrying about rust. It's almost never actually on me, just available.
So between the two, I could probably handle all of my daily cutting tasks. However, since I like and enjoy pocket knives, I usually have another slipjoint knife (Case, Buck, or Victorinox) in my back pocket beside my wallet. It does get used, but I could have probably gotten by with the Boker for most of those times.