So much depends on what you do and how you camp.
When we winter camp in below freezing nights we dry camp. We use an electric heater to keep the TT in the mid 40's at night and usually with sunshine and other activities such as cooking, the TT is in the mid 50s during the day.
If we were in the TT for any length of time, we would need more heat but we are usually at an event doing something outside like snowshoeing, bird count, or other winter oriented activities. Often the event include some indoor activities also.
There is a big difference between a sunny day in February in the high 30s and an overcast and windy day in December.
Our furnace can bring our TT into the mid 60s in a few minutes if we need too. I would say that on average we are in the TT and hour in the morning, an hour at lunch time, and perhaps three or four hours in the evening before bed. The evening hours are about the only time we use the furnace.
So, as you can see, everybody's camping style will effect how and how much heat they need. We see folks tent camping in the snow. That is something we have not done in several decades.
Take care.