I read this in a jelly roll book I bought and have started to use this method when cutting strips for any kind of quilt.
"If you have strips that have been cut selvage to selvage(WOF) along the crosswise grain (which most are as it is easiest), just cut the strips in half on the fold. This works well for a number of reasons.
- it helps keep fabrics on-grain and eliminates the bowing or curving that may occur when fabrics of differing thread counts are used.
- You can get more fabric variation in your quilt design also.
- You can use fat quarters too
- some pre-cut jelly rolls don't have many multiples and this lends itself to more variation."
The above quote is taken from
Nancy J. Martin's Rolling Along - Easy Quilts from 2 1/2 strips ISBN:978-1-56477-841-3 p. 13.
I found out even in high end fabric the strips can curve when sewing the longer strips together.