Never flew a turboprop aircraft with idle or rich mixture. Up in Alaska, when it got cold (< -40) and we didn’t have a Herman Nelson, we would tie the prop down and start the engine (you can do that on the PT-6 series) and let the oil temps creep up before introducing the oil into the propeller governor. More for limiting blown gaskets, otherwise keep the engine in feather until temps have stabilized.
Yup, flying around in bunny boots and a down parka, don't miss it at all.