Lines and patterns can be used in art journaling to add emphasis or embellish. Pen and ink strokes such as contour lines, parallel lines, cross-hatching, stippling, scribbling, wavy lines and criss-cross lines are described in Art Teachers Resource.
In All at Once, Jennifer emphasizes the sense of frustration and chaos using scribbles, cross-hatching, etc. It really pops on the dark background, giving the feel of graffiti or sidewalk chalk. The process is described at her blog, Life in the Arizona Desert. Shared with permission.
Lots of line love in Randi Feuerhelm-Watts Journal Pages and Joei Lau's My Moleskine B-3. In his illustration of Oregan Nut Brown Ale, it's clear that Kurt Hollomon is a master of the line. I learned of his art through Danny Gregory's Illustrated Life Podcasts.
Please share what you create!