As you can see there is no one answer. We know the factories in Indiana do not bring the TTs inside during the winters and the units sit outside at the dealerships.
When I purchased mine in December it had a sticker indicating it had been winterized. I assumed that was because it was a used unit and may have water in it prior to my purchase. Also, since the TT was on the sales lot and not plugged in, the battery had been removed.
When I brought the TT home I set it next to the house so I could remove the snow when I was over 6 inches or so. Many people do not do that either.
This year I am trying a TT cover and will keep it powered but not heated. The DW and I have been known to take it out for a mid-winter weekend of snow shoeing at the State Park.