How it works: Spend 20 minutes shelling, cutting and rinsing 4 acorns times a batch of 20 for total of 8 hours.
How it could work: Spend 2 hours shelling, cutting and rinsing 100 acorns. Put all of them inside an oven for 4 hours to roast, or put 20 of them at a time inside a pot, put the pot inside a fire and go about your business while they cook.
In short, introduce the charcoal-making mechanic to cooking and limit the batch to the size of container; eg a tin can vs a pot vs an oven vs a cauldron.