@KalamaQuilts your comment could not have come at a more crucial and helpful decision point!!!
I am working on a quilt at the moment. Top is nearly done and I was going the direction of making an “afterquilt” on the back, using up all the bobs and bits of leftover fabric. As I was making progress, doubts crept in:
(1) There is enough to make it a second quilt top (with considerable negative space, but I like that).
(2) extra seams on the back make it less cuddly/soft to use
(3) it’ll be more fiddly to sandwich and align
(4) it felt wasteful to piece something and shove it on the back
But your comment brought me back to reality. I don’t want to make two quilts with this fabric, I don’t have intended use/recipient, I made it because I wanted to. I don’t want to pay for twice the batting, sandwich twice, quilt twice, or bind twice! Onto the back it goes!