Years ago when one had to take home ec, we had to pull a string the width of the fabric to find the strait of the grain. After cutting on that line, we had to stretch the fabric so the selvages would line up before we could place the pattern pieces.
Now days if your fabric is ripped then washted when you get it home it's already to go. And as a bonus, when you cut your strips on the grain, it won't have all those unraveled threads when you're working on your project.
Love it when it's ripped!