Each charge is a bet. You spend gun powder now to find out whether the ground under your feet will pay sulfur back through a mining quarry. A spot that reads poorly still costs the whole charge, so throw only where you would really build: close to the base, on ground you can hold.
The batches help. Powder and fuel both divide evenly into a charge, so any number of charges leaves nothing on the bench. The slow line is the low grade fuel: five crafts of it per charge, more than half the time at the bench, and a fair amount of animal fat behind it. Hunt before you queue a batch.
Tip
Hold off on the blueprint until a quarry sits in your box. It is one of the dearest at the Level 2 bench, and without a quarry or a pump jack the charge tells you nothing you can use. Spares give back about half their powder and fuel in the recycler.
