I am making a Virginia Reel quilt, its very similar to a flying geese block. I started with templates made from the book and then I bought Marti Michelles flying geese ruler and the angles are just different enough that I either start over, after 12 blocks, or continue with my battered templates.
This made me take a second look at my 30 degree triangle rulers. Guess what, they are ALL slightly different. So, Ladies, stick with one ruler throughout each quilt. Oh, by the way, you have to make a triangle with each ruler and stack them to see the differences.