Cardboard cutting........How much cardboard dulls your knife????

[Obsessed with Edges]

IME you should be able to cut 20-30 feet with no real wear. As others have mentioned, geometry and grind play a major role. Also, if the box is sealed with plastic tape instead of reinforced paper tape, the adhesive will seem to wreck many an edge - wash it off with denatured or rubbing alcohol and you're back in the game.

Yep. I've also come across some heavy cardboard that had some real nasty glues/adhesives/binders in it, between the layers. Really gummed up the blade fast, so much that the blade was binding in the cut. Almost like coating the blade in sticky, gooey epoxy. Once the blade was cleaned up though, back to normal.