A good 25 years before zentangles even had a name or were a 'thing', I was creating them.
Sometimes the sermons were such that I took virtually no notes and a particular image did not come to mind. That's when zentangles came into play. I could draw and color quietly while still keeping my mind on what was being taught.
Outlines done in black, very fine point, ballpoint pen and colored with reds & purples in prismacolor colored pencils.