Interesting. I haven't had any problem using the slotted rulers with any size or brand of rotary cutter. Everyone holds the cutter differently but I was taught by the JT rep at a quilt show how to cut correctly, always start the cutter at the top of the big teardrop slot and then pull it back to the beginning and then make the cut in one pass. Hold the cutter straight up at a 45 degree angle. Do hot tilt the cutter to one side. I spend a lot of time at many vendor booths when I go to a show and ask dozens of questions how they do what they do to make perfect demos using their tools. They always have tips to making the tools easier to use.