I studied and used perspective back in college and still apply it to some drawings, BUT never with my urban sketches. It was enlightening! Alissa and I did get the basic 2-point perspective finished and I for one felt I'd achieved a lot.
Back at CCCB, I attended Fred Lynch's fantastic talk, then headed for the metro to join WWSketchcrawl #40 and the end of the symposium. I have never seen so many sketchers in one place - it was amazing! The symposium participants and organisers were joined by the off-symposium attendies, and local sketchers. Numbers vary but the paper said there were 500 sketchers!