Due to a rather intense rain storm, I split this banner into two parts. The first 11 missions at the botanical gardens took about an hour.
I completed the remaining missions on a Sunday morning during the summer semester. Very few people on campus and minimal parking concerns. The previous poster had different obstacles, which I could imagine when the students are in campus.
I ended up parking at a few of the decks which worked for me. The remaining 19 missions took about 4-5 hours.
Overall, a very enjoyable banner. The Creator tells you that you will be spending a lot of time completing this, so there is no surprise.
The mission was well laid out and pathing was good, until mission 14. The entire set of missions has you all over Anacostia, until mission 14 sends you to Catholic University for no purpose. If you're walking, you're going to be pissed. I recommend the owner fixes this banner.
Update - Appears the Poetry museum moved from Anacostia to Brookland, so be prepared to do some travelling.