I wondered about that and thought about getting a skein to see if I could gauge or close to it...I know the sport gets 6sts per inch on #3-5 needles...while the worsted gets 4.5 to 5" on 6-9 needles...When you look at her pictures she has one of a ruler by her sts and it looks like she is getting 3.5 or 4sts per inch...
With a blanket normally I wouldn't worry about gauge 'cause it doesn't have to fit...but not sure how the different yarns would come into play with how much yardage you would need
