New discovery for me.
This morning I was lining up sashing strips with rows of blocks and putting in pins to mark center. Well pins kept falling out or sticking me and then the light bulb in my brain went off. I went to my table and marked with pencil the center of all my sashing strips, both sides, and then marked the center of all my rows since I had a piece of sashing in the center. Pinning went much faster and I'm thinking why didn't I know about this before. If someone else has posted this method, I haven't seen it. Hope this helps someone else.