OK, a bit of clarification needed. When a block is 'finished' it usually means all sewn into the quilt. Some folks refer to a finished block size as when the block is completed, before it's joined into the quilt. Which are you referring to?
The log cabin kit that you talk about to actually finishes at 9 5/8". The unfinished block is 10 1/8
https://jordanfabrics.com/products/m...ll-impressions
There are 7 equal patches across the 9 5/8" finished block. So each strip finishes at 1.375" (9 5/8" divided by 7). If you add the seam allowance back on, each strip would start at 1.875". Something that's probably causing a bit of confusion with this specific kit is that it's
flannel. I'm guessing that you are correct in that the strips start out at 2", but flannel takes up more room in the seam. If you used quilting cotton, and started out with 2" strips and maintained your quarter inch seam, and had the same number of rounds as the Jordan example, you would end up with a block that measures 11" before you sew it into the quilt, and 10.5" when joined.
I guess what are you trying to do? Specifically use 2" strips? end up with a 10" block (after sewn into the quilt)? or a 10" block before you sew it in?
There would be different solutions depending on your goal!