I think the information on the label is what would be 'average' for that yarn and it's also the size used to determine the approximate gauge of the yarn. You can basically use any size needle you want to get the fabric you want.
Of course, you can go too big and get loose floppy fabric, or too small and have it stand up by itself. It's really what you want to do with it. There are no hard and fast rules. I use the needle size as a guideline.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry