Here is an 8 1/2" X 11" zentangle that I made for my large journal. I've done several of these recently and this one was made very quickly in free minutes here and there over the course of about a week. I don't think I ever worked on it for more than 15 minutes at a time. It's certainly not my best, lol.
If you'd like to see some of the other zentangle pages posted previously, check the sidebar links with the label zentangle.