Over the past few years, my two friends Chet and Don, have been coaching me on knapping, and it's amazing what can be done with a little sharp tool. I've got a little obsidian blade I made with a 1 1/2 inch blade and a wood handle fixed on with artificial sinew. It's about the size of a Buck Hartsook. I made a deerskin pocket sheath for it, and it's cut some things well.
I've also been using the heck out of my sak classic for most of my light pocket knife cutting. Mail, twine, breaking down boxes after a trip to Sam's Club. Just as an exersise in maximum minimalisim.
For most cutting, you don't really need much blade, the handle size is the more limiting factor; what can you hold onto with your hand size? There's where it get's personal.
On the 4th, we had a BBQ for the family, and I had a couple of large fillets of salmon that I'd marrinated, and before putting them on the Weber, I cut them up to smaller pieces for easier handling with tongs. I did the cutting with my little obsidian knife, and it went right through the raw fish. Then I cut up the marrinated sirloin into peices because some wanted medium, others well done. It went right through the raw beef like a...for lack of a better phrase...a sharp knife.
It's a ballance of needs and wants. What do you need, and how much do you want to carry around. My own view of this has changed greatly over the course of my life. These days I want the smallest lightest tool that will still let me do the job if I'm careful.
When I was a kid, the standard deer knife was Little Finn. About a fingers worth of blade. The Icemans flint knife was about a 2 inch blade. He must have skinned that bearskin cloak he was wearing with it, and whatever game he killed. He was well dressed for the cold with some nice hide/fur clothing. If he had not been shot in the back with that arrow he would have been okay.
I can get by with a pen kinfe size blade if I have to.