i accidentally discovered the joy of piecing with a universal size 10. it's perfect for the thinner fabs that some of us like to scarf up from a "certain store". it works well on most other quilting weights, too, although i also bought a stock of 11s and 12s for those.
i haven't played enough yet to decide which i'll like best for quilting. so far it's been 11s and 14s. i just broke down and bought a roll of warm & natural AND treated myself to 11 & 14 quilting needles. the w&n is very different to any of the batting i've used before so experiments are in my not so distant future. :roll:
P.S. if the stitching looks good, doesn't appear to damage the fabric, and the seams are sturdy, i'd say the needle is "right" no matter what it was. Necessity and Budget are the Mother and favorite Aunt of "use what's on hand and gets the job done." :wink: