When laying out a pattern, the grain of the fabric will have the stripes running up and down. While in an upscale boutique I spotted the stripes on the yoke running horizontal. My first thought was, "That is wrong." My second thought was, "That is different, and I like it!" It just added a little interest to the garment and might come in handy when you are running short on fabric.
Are you a rule breaker when you sew?