"R" writes from Jamaica, New York: "I have used duct tape to repair the paper vapor retarder. I'm curious, is there any benefit to running duct tape over the flanges after they have been stapled to the studs?"

Answer: There may be some extremely minimal benefit in thermal performance but to be honest I don't think it is worth all the extra work. You can probably have a greater impact by adding more insulation in the attic, switching to compact fluorescent light bulbs or sealing out any air coming through penetrations for electrical wires, plumbing or utility boxes.