Don't forget. Most knives (home use) don't get dull from cutting stuff. They get dull from corrosion. After every use, wash with hot water and wipe COMPLETELY dry. They store them in open air (I throw the fillet knife in the drawer not in the sheath). They will stay sharper MUCH longer. And never put them in the dish washer, ever.
Using the same logic, I can get a 3 blade shaving razor to last 6+ months easily.
-John