Well, I either googled or YT this topic once because I had always pressed open. I discovered that the seams are stronger when pressing to the side as the fabric is pulled upon during use. Whereas, when you press open, the thread is being pulled, which is not as strong as fabric. That made sense to me.
So, I developed a system for pressing to left or right by using even and odd pieces, rows, etc.
Odd rows get pressed right, even-to the left. Then they nest, which is a new process for me.