In the summer time, it's start & go with the exception of buckling-up and adjusting seat & mirrors. Oh IDK, 10-15 seconds?
In the winter time, we often use RES. And if there is a ton of snow on the vehicle, I do what ever it takes to remove the snow just to get in the car to start it. And then run the engine while cleaning off the rest of the vehicle in order to see clearly. Again IDK, 10-15 minutes?
In the past on several occasions, I have left my vehicles running for over 45 minutes while snowplowing the driveway, forgetting that I had them running...with the heater on HIGH!. Man, were they nice and warm!
We like getting into a warm vehicle that we can see out of. And in todays vehicles, I like to make sure(the best that I can), clean the cameras, sensors & head lights(without scratching) before driving off and that the wipers aren't full of ice on those below ZERO mornings and blustery days.
In my area, if there is a boat load of snow atop the roof of the vehicle, you can get pulled over by the police for not cleaning off the snow. As there have been a number of incidents where the snow lifted off the roof while driving and hit the car behind. I have never seen anyone get pulled over for this but it can happen. However, I have seen a sheet of ice lift off the roof of many vehicle while at speed and crash to the ground almost hitting the vehicle behind. NOT COOL!