We always carry 3 knives but not exactly all are combative knives.
I'm glad I'm not the only one who carries three!

My keychain has a small Swiss Army Knife on it (with nail-nippers, tiny scissors, tweezers, etc.), I keep a Leatherman Tool on my belt (for pliers, screwdrivers, cap lifter, saw, etc.), and a medium sized (3.5 inch blade) folder in my pocket (usually a micarta-inlayed Chris Reeve Sebenza with dual thumb-lugs, though I have others that make the rotation). All three are primarily tools, though the folder could potentially have defensive uses if my life were on the line.