When I moved in, I re-balanced the system by playing with registers and dampers and got it to where the furnace would run once an hour for 20-25 minutes, and the temperatures in the rooms were much more even. It was pretty bad before that.
Now that I have the insulation, the furnace runs 10-12 minutes, then is off for 15-20 minutes, and then runs again for 10-12 minutes. I'm wondering if the insulation was a good thing or a bad thing now... Shouldn't the furnace run LESS often?