I currently live in Romania, but in the area where I live, the temperatures are usually much lower throughout the year, and especially during winter. So far, this year, the lowest recorded was about -9, but I am expecting even lower temperatures in Dec/Jan. As you said, I am taking it easy when I take off, but this is more like my usual driving style, if I can call it like that.
You kinda guessed right, I have heard that this might be a recommended practice for petrol/diesel engines, however if that's not the case here, then probably I should disregard this kind of concerns that aren't really concerns.
"Modern engine longevity owes a lot to the use if heated front and rear screens in winter." - might sound dumb, but how the longevity of the engine is related to the use of front and rear screens in winter?