The writer's only responsibility is to his art. He will be completely ruthless if he is a good one. He has a dream. It anguishes him so much he must get rid of it. He has no peace until then.
When making something, always get a few extras — extra material, extra parts, extra space, extra finishes. The extras serve as backups for mistakes, reduce stress, and fill your inventory for the future. They are the cheapest insurance.