We have looked at delivery bags from time to time and while there is some difference between bags of different manufacturers, the biggest difference that we found was due to the number of pizzas in the bag. Using 140F as the cut-off temperature, we found that a single pizza in a bag sized to hold a single pizza was good for about 30-minutes at most, while two pizzas in a bag sized for two pizzas was good for about 45-minutes. When we did three pizzas we got something close to an hour. Keep in mind that this was for conventional bags. If you use one of the high-tech bags with the heated ceramic disk I'm betting that you can best these numbers. You will need to do the work to find out what those times are though as we have not done any studies using any of these bags.
Tom Lehmann/The Dough Doctor