I'm a Learn to Quilt teacher at my LQS, and I always tell my students that there is only one hard and fast rule they need to observe: close the safety on your rotary cutter each time you place the cutter down on the mat. I worry that someone will be smoothing out fabric with two hands, and smooth their fingers right into an open blade! I explain which methods have worked best for me (and why), but that there are many ways to accomplish things, and to choose what works best for them.