I read through the answers and saw where others have problems with regular rulers vs. the JT shape cut. I use my JT then purchased the Creative Grids Stripology which is much more substantial.What I use is the Quilter's Sidelock.
https://www.quiltersslidelock.com/ab...ers-slidelock/ I have a healthy fear of the rotary cutter and the Quilter's Sidelock allows me to be away from the blade, it holds the fabric in place. When using the Creative Grids slotted ruler I do as Dina in post #2 described. Place the Quilter's Sidelock on top of the slotted ruler lock it down and cut. I believe have been discussions on the boards here about the Quilter's Sidelock for me since using this tool my wayward cutting adventures no longer happen.