While this isn't directly related to the theme, "highly prized", I'm using my sketchbooks quite heavily these days, working through my ideas for where I want to take my stacked journaling design idea.
The page above was created with Fineline markers and stacked journaling- the word green, to be exact, which is what created the loopy bits to the outsides of the leaves and the great texture in both the leaves and the stem. So far I haven't found any design that I haven't been able to enhance with some form of stacked journaling.
Here, stacked journaling was screened onto a previously painted sketchbook page using a Thermofax screen and black textile paint.
Stacked journaling was used here to create shapes on fabric which was then mounted into my sketchbook with fluid matte medium and "coffee stained" with fluid acrylic paint.
More screening of stacked journaling, adding depth to a previously sketched, screened, and painted page...
Stacked journaling on top of the existing text and Notan-like design of an old, yellowed telephone book page, cut and mounted into my sketchbook....
As you can see, I use my sketchbooks to do more than sketch. They are the incubator of ideas which will grow and develop organically, as I work each page in my own particular way.
Please don't be afraid to test yourselves, to put pencil to paper and make marks that are uniquely your own. It may seem hard at first, and scary, but I promise you that those first exploratory marks, when viewed over time, can not only improve your design and sketching skills, they can also become very dear to your heart.