a traveler's notebook isn't really a notebook. It's a notebook cover that holds several smaller notebooks.
When the notebooks are full, one can simply take them out and put new ones in.
Now, I go through a lot of notebooks. There's always one or two in my bag. I have a book for my bullet journal, one for my weaving patterns, one for my garden, one for my writing drafts, one for my knitting, a spare one, one for my bag... There's a lot. I love the A5 size and my absolute favourite so far are these thin volumes with a kraft paper cover. The problem with the thin journals is that they don't hold up to daily wear and tear. Thicker books are nice, but having half a dozen notebooks in my bag at one time is crazy heavy. I also hate to start a big notebook only to discover that the paper quality isn't sufficient for a fountain pen.
We can buy notebooks inserts and covers. Amazon has some lovely A5 size inserts with nice quality paper.
Or we can make our own. That way we have full control over the size and quality.
I have been using a notebook like this for a couple of weeks now. It's fantastic!
Normally I have four or five active notebooks at any one time.
One grid paper for weaving
One blank paper for brainstorming and mind-dumps
One lined paper for the same
One dot paper for planning and bullet journal
And then one notebook for whatever project(s) I'm working on.
Keeping these notebooks sorted and accessible is a chore. Having one in my bag is fine, but three or five... or more. Too heavy.
I got an A5 sized notebook because that's the size I like to write. At the moment I have three notebooks (one for research, one for brainstorming and notes, one for recipes) and a copy of Politics and the English Language by George Orwell. The individual notebooks are smaller than I usually use, having only 60-ish pages instead of the 200 plus pages the big notebooks have. But that's proving to be a good thing as my attention span is never quite up to filling a full-size notebook all the way.
I printed out and cut the paper for making my own insert, but it turns out my stapler won't reach that far. I'm wondering if I can use my sewing machine, but it's currently under a pile of seed starting supplies.