I have made several modern quilts by Ringle & Kerr, and they will often tell you to press the seams open. It's a lot more work, but I have found that if I don't do it, I often end up with seams where both sides are pressed in the same direction. Not good. When the seams are pressed open, there's never a problem. I pin carefully, and I find that my intersections look about the same if I nest them or not. I think it's all a matter of personal preference.