Happylab -- you're tearing up that yardage! Good going! I say, if you use a sheet for backing, that is yardage out from your stash, f'sure!! You get to make up the rules on how you want to reackon your succeses, however. I am just an enabler.
JoAnn's has a $5/yard novelty sale going on right now. I got ten yards. I'm still walking behind the wagon but I'm loving my fabric choices!! I haven't been to JoAnn's for a long time.... I used to go weekly.