I was watching the same Leah Day video and it seems to me that she mentioned the fact that some quilters feel the seam has to be pressed to one side to make the quilt stronger. However, her comment was that she has been quilter for a long time and never had a problem. But she did mention that when she was piecing, she set her stitch length at 1.5. I personally have never pressed the seam to one side. Seems to me that it would be very bulky. However, I must mention that I have never encountered the quilt police so probably have been quilting ignorant all these years. But you know what;
I am happy in my ignorance, so there!