As the title states. It would be convenient to be able to stoke the files multiple times. You only get 5 uses when you stoke the fires, and that often leaves an uneven amount left for the next trip to and from the mines.
If we could keep adding the stoking, it would be a lot easier to keep track of, and be of more use. The only downside I can see to this would be users potentially paying once a day and letting them build up, but that's really no difference than someone only mining and using it once a day, and would take a lot of time to set up.