The first set they ran with 2 days in between each car, the second set they ran, so far, with 3 day in between each car. That puts the Dining Car to run on the 21st. That will leave 11 days from the last car until the end of the event. On beta, there were 10 days between the last car and the end of the event. No real difference.
Now, why would Inno run them this way? Because after the last car has run as a daily special, the only other way to get more cars is to buy the reindeer collection. The reindeer might also contain one or more WT upgrades making it even sweeter. Many won't buy, but many will. Either way, Inno wins. Any sales of reindeer are sales they didn't have last year.
No. I don't think we'll see them a 3rd time. Inno has reindeer sales to drive. Because of this, they may get some of mine yet. In one city, at least. We'll see, but it will be dependent on the number of cars on the collection. No matter how many I have and may still get, I still want more. Since the diamonds I'll use are all free, they might get them for more cars.