Does anyone here have experience with crafting their own notebook?

I was reading a bit about how to do it, and I think I want to sew several signatures together with coptic stitch, and sew those onto a leather wrap, so that the book opens flat and feels flexible. The thing is that I want to use mixed media paper which is pretty thick, and I wonder how many pages I can realistically have, before the book becomes uncomfortable to write in? I am thinking of using 5 sheets per signature, and 20 signatures, so that would be 200 pages.