I was on a jury last year, we took 15 min to figure out who was the foreman, and 10 min to convict the guy. The lawyers there said a quick verdict usually meant guilt, because everyone was in agreement quickly.
...and it's juries like you that hate guys like the guy from 12 Angry Men, Matlock, and Monk (and probably me as I haven't sat on a jury yet - where's that sheet of wood?) that completely throw the half hour conviction right out the window.