Yeah well all who have been reading my ramblings for a while know I usually use unpieced backs which is not really a problem as long as my quilts aren't wider than 59" (150cm) and even if I go bigger it only makes the selection smaller but I can easily go up to 110" (280cm). And funnily even though I measure my blocks and sashing and everything in inch - as soon as it comes to measureing the whole thing I take out my metric tools - I still can't think in inch when anything get's bigger than 12" and even then I my "idea" of how big the thing is rarely the actual size [12 inch are damn huge]. Same as I still sometimes catch myself at converting the €uros to the old curency - yeah the inch centimetre thing will take some more years.
So yeah I don't use the fabrics from the front in the back as I never have enough for the front pattern and a complete back. So I go hunting looking for the perfect backing fabrics and sometimes I find something - like the one on the left. I saw it, I bought it, now I'm basting it.