For me I have had much better luck sewing each segment together, pressing seams in the same direction so they travel around the block all going the same way, instead of trying to line up the 2 halves. I found with my lone Stars that they come out perfect & lay flat when I do them each segment individually. When I try the (2-halves) method I wind up using my seam ripper A Lot! And, never get it right until I take a number of segments apart & start over- one at a time. For me it is faster and much more accurate