I leave the turntable in. Do note the warmup time (YMMV) and either take the time to pre-heat when the cooking instructions call for it, or add time to the specified baking time to account for it.
I frequently do frozen biscuits and have found that the official 20 minutes, which is perfect for a pre-heated oven, requires 24 minutes if I don't pre-heat. The turntable does insure even cooking/browning, which if you think about it, would be a problem, since having all the heat coming from one side could be expected to cook unevenly.