I managed to 'squeak by' on a tad over 2 tons last year. I fired up in early Dec and shut down in early Mar as I had to go out of town. I'm heating only the first floor of my cape-cod style house, roughly 1200 feet, give or take.
Although it was considerably more mild this past winter, I also made significant changes to the ducting in and out of my Alaska Channing III. Basically, I reworked it to remove 5 90 degree turns and about 30' of horizontal run on the cold air return side, thus achieving a better air flow. My stove is in the basement, next to the forced-air furnace. Having built a 'jacket' for the stove 2 seasons ago reduced coal usage by about 15-20% from what I was burning before building the jacket.
In short, it's all about having a complete air 'circuit', and making sure as much heat as possible gets upstairs and not into the basement!