I think it’s interesting to see how the “standard” seam allowance evolved during the “quick quilt making” revolution in the late 1970’s to now. When Barbara Johanna’s published her books Quick Quilting and The Quick Quiltmaking Handbook in 1976 and 1979 respectively, she suggested a 1/2” seam allowance. By the time Barbara published Crystal Piecing in 1993, the 1/4” seam was the norm (although her technique of mark-sew-cut was the same as in her earlier books, and the cutting was often completed with scissors).
When Mary Ellen Hopkins began teaching quilt shops her techniques in 1982 to allow the quiltmaker to say “It’s Okay for you to Sit on My Quilt”, she used a seam allowance of whatever you got when you lined up your fabric next to your presser foot and then had you use that measurement for the entire quilt. She noted in the revised version of her book from 1987, that often the presser foot measurement was 1/4”.