I started my Cathedral Window quilt back in 2009 and is a work in progress. Basically I got discouraged and stopped working on it, out it out of sight, out of mind. I felt as if I simply could not finish it by hand. It got too big and was hard to manage. I use a 9 1/2 inch square for the base and stitch it by machine. I sew the "windows" in by hand working on a block at a time. The blocks are approximately 16 inches.
Thanks to your question, I got a wild hair and pulled it out last night and managed to sew in about 12 little windows before bedtime. I know and accept that I will not finish this as a complete "hand project" but have decided that I will sew the windows by machine as it gets larger.
As for information for you, here is a link from 2010 to a machine stitched Cathedral Window tutorial by Eddie that gives step by step instructions. Hope it helps.
A search of this forum will also yield a lot of information on CW quilts as well.
Machine Stitched Cathedral Window Tutorial