It is nice to have the same sketchbook on the shelf, but it isn’t important. I think finding paper that works well enough in a sketchbook format is key. So far I’ve been enjoying the Stillman & Birn Delta Series in softcover. It takes a light wash and has a nice ivory tint which is great for bright outdoor days. I had a hardcover S&B some time ago, but it is a little too heavy for my backpack. The soft-covers are sturdy enough to endure being rummaged through repeatedly. I am down to my last few pages in this book, hopefully my order has come in at the local art store.