I recently did some mozzarella sticks (they make good snacks for work, don't laugh) and did the soldering iron in the tin can trick. 2 hours was too much, of course I had the smoke just rolling off the thing. I would also venture to say it depends on how much of a smoke flavor you want to impart, heavy or just a kiss of smoke. I had really heavy smoke on mine.
22.5" Weber One Touch Gold, New Braunfels El Dorado, Country Smoker TG-300 Tailgater