Most of us don't use the setbacks because coal reacts slowly.
If you do, I would go more than a degree and hour change, Coal takes time to react (not like gas or propabe furnaces that are instant heat) and it may take way longer to bring the temps up and then it overshoots and stays hot for a longer period, then goes below the setpoint and the cycle starts all over again....
I usually leave mine on about 67-68 most of the time and it maintains it pretty good. I do have it set back at 11pm to 66 or 67 in case I raise it to 70 or so when home, then it sets it back if I forget.
Good luck, you can experiment, but you will quickly notice the overshoots/undershoots of the temps if there is too much temperature swings.
The Coaltrol will save you money by setting the feed rate back when not needed and maintain smaller fires to satisfy the temps. If the sun comes out and helps heat you house, it will pretty much go into an idle mode.