I call it an L shape because that's the way I put it on. Doesn't really matter which side is which so long as you do it consistently, so do what makes sense to you -- could be top and right or right and bottom as well as left and bottom. Some fabric designs hide seams but white solid it will show, for me consistency matters. For others, not so much. When I lay out a top, I always number my blocks (alpha across, numbers down) because no matter how careful I am, I always turn something or drop them or something that messes them up. I pin the block number in the upper left corner, again, it doesn't matte where you do it so long as it is consistent.
My most recent project I had to use what I call the "two unwieldy strips" method because I was using a striped fabric and it was important for me that it ran in one direction, so I cut it from the length of the yardage and not across. So not every quilt calls for the same treatment, but if I possibly can, I opt for the L method
