I've only cooked twice on my week-old UDS, but I used the KISS method with 8 1/2" holes in a 15" diameter across the top of my flat lid. So far it's worked great and seems to offer plenty of exhaust, neither of my meals were ashy/sooty. In fact, despite calibrating my thermo, I've worried through both cooks that it was stuck because it held at the exact temp I wanted it to for the couple of hours I needed.
I also smoke on my patio with a large overhang so it's safe from precipitation. In furthering the KISS method, when it's time to choke the flame, I shut off my intake(s) and tear off small bits of aluminum foil to plug the holes. I do so in a manner similar to bits of toilet paper on your bleeding shaving nicks. Leaving the bits flat, I use my fingertip to settle them down somewhat into the holes and then I use my palm to flatten the foil around the holes. Simple and secure and within an hour or so my thermo reads ambient temps.