I made This clam shell quilt years ago. I used up hundreds of scraps doing it. The picture is here in my album here
https://www.quiltingboard.com/member...bums20172.html it is the last picture. I did it all by hand and I don't trust myself with the machine on curves that much.
If doing it by machine now I may consider pinning and stitching just the way you are mentioning. I am a bit more confident now a days.