i use up my scraps all the time...have never paid any attention to such things as bias edges...have lots of them in fact since i save all those little corner triangles i cut off...still very usable. and when i fussy cut the left over swiss-cheese piece of fabric is stripped-cut into usable pieces...if i was making a dress/skirt that had to hang a certain way i'd worry about grain lines...making quilts? i don't worry about such things
my grandmother made fabulous wonderful quilts i don't think she ever bought a yard of fabric for one...she recycled...used what was too worn out to wear anymore and made quilts...she would not have been able to accomplish any of her beautiful award winning quilts if she had worried about grain-lines and bias edges