When I made mine, I assembled it like Jan describes making several blocks at once in a chain piece method. I also precut my logs to size, not all of them. I would cut some, make some, lather rinse repeat. Another thing I did to speed up assembly was I finger pressed between logs and only iron pressed when the block was complete. I made 6.6" unfinished blocks and had a grand total of 168 blocks. It was my "mindless" sewing project and I was able to sew blocks together even when I only had 10 or 15 minutes to sit down to sew. It seemed to go together quickly. What took a long time was waiting its turn to quilt it.
It is one of my favorite quilts and is my regular bed quilt. Here is a link to pics I posted of it.
Scrappy log cabin clam shell setting