Mrs Grendel gets scrapbooking magazines from time to time (actually its more regular than that as see seems to subscribe to several).
Often these magazines, as well as having photos of other people's layouts, will also have a sample of paper in them as well.
It has a fold in the middle, and is not 12 by 12 inches, and yet the layouts pictured show the layout ON A 12 BY 12 INCH SHEET OF THE SAME PAPER!
So why bother putting in an undersized piece at all?
I can't remember Mrs Grendel ever using the stuff from the magazine and I suspect the same may be true for other scrappers.
I reckon there may be a whole industry waiting out there for someone to collect all these odd sized pieces and turn them into origami spacecraft.