Oh, say...there are really only 10 "Y" seams (totally not meaning to be argumentative) at least the way I have always put the Lone Stars together. I would sew three diamonds together, straight line seams. Do the same with the next three diamonds, now you have two halves. Place both halves together and sew one straight seam down the center. No "Y's" there! As long as you match your center with a pin and sew from the center outward when putting the two halves together your seams should all meet in the center. 1/4 inch seams are very very important for this type of block to come out correctly. Just FYI.
Rose