Very interesting! I have a 36" x 68" white board such as you describe (made by Sew/Fit Co. in IL) that I've had since I first started quilting; it is the same size as my plywood "table top". I've always done all my rotary cutting on it while the smaller cutting boards just hang on the wall and never get used. So I do not know if the blades would last longer if I used the smaller boards; I must try it when I cut something small. I do love the fact that I can cut long lengths of fabric on the big board without having to fold it; for me, that trumps my blades getting dull.