When cutting with a rotary cutter and rulers I always cut larger do my piecing and cut down. That is a standard for me. I can never cut straight triangles or seams so I always need to square things up to be precise. I bought the Accuquilt system a little over a year ago and have discovered the perfect cuts help me out better thought I still find it necessary to trim down sometimes as my 1/4" is sometimes not the Accuquilt 1/4". It all works out though and the accuracy is what is important thing. You can't make something larger but you can always cut down.