many times patterns are designed to (fit the blocks)
if you look through historical pictures a quilt fit the top of a bed---they did not include over hang---
(we) have decided we want the overhang on our quilts and have to adjust our patterns to make that work- either by making more blocks-expanding the design- or add borders-
back in the day- a quilt with an overhang was not a quilt- it was a bedspread