SITD on a long arm is like driving one of those grocery carts where every wheel wants to go its own way. I am better at SITD than I used to be...and some days are better than others. If I hit a day that is NOT good, I do something else! I only quilt for myself and occasionally a friend or two. Rulers are the way to go...and practice. I find that diagonal lines are the hardest. I DO think that on some quilts, it makes the quilt.