One of my quilting groups will spend a day a few times a year where we get together and ZigZag sew the pieces together to fit some of our quilts as batting. Once I had 4 different kinds of batting and I asked about that. Our very skilled [and I mean this!] leader said it didn't matter as it was for charity/utility quilts. Guess what? once it was in a quilt you really didn't notice the difference.
This from a group that does over 1000 charity quilts a year.
It works.
Smaller pieces of batting go to the Humane society group and they use that for pet beds/blankets they make.
AliKat