Does your piecing indicate you are getting accurate cuts?
I used to use my mat as a measurement, no more. I was not getting accurate cuts. I now use a two ruler method. The ruler on the left is my "cutting line" ruler. I use a "measuring ruler" on the right to measure from the edge of the fabric to the amount I want to cut - place my "cutting ruler" along the left edge of the "measuring ruler" - remove the "measuring ruler" and cut along the right edge of the "cutting ruler".
A lot of the quilts I make use small pieces. The smaller the piece, the more accuracy required (I can't ease in a 1/4" on a 1" piece, but I can easily ease in 1/4" on a 12" piece).