I use Olfas and mine seem to last as long as they always have. I have a separate one that I use when trimming up quilts after quilting as the poly in the battings (80/20) do seem to wear the blades out a little faster. Just a thought when you change your blades are you putting your cutter back together properly? I think they have a video out on the Olfa site. Also holding your cutter at the correct angle makes a huge difference in how it cuts.