If we go to 1/2 inch it still has to be accurate. They do have rulers that add a 1/4 inch seam that could be used on a piece that has the seam allowance figured in. I have a friend that sews "flat out"...really fast but I find I do best when I go rather slow and feed my piece in evenly so that I don't veer at the end. That's where I have had the most problems. As for keeping the block square, I'm finding how I press makes all the world of difference. Still working on that one!