No problem with mine. I just finished cutting out and trimming my Log Cabin blocks for my watermelon quilt and no problems. Sometimes I cut out 6 layers of fabric that were 2" x WOF then cut down to sizes needed.
I have used the 10" mark on my mat alot to cut on and I had to change cutting spots as no blade will cut well in the groove on the 10" mark. Other than that, no problem.