What was the “system” that Ann and Loomis had?

For about ten days, Ann and Mr. Loomis have a system: Ann goes down in the morning to gather milk, get the eggs, feed the chickens, work the garden, and pick the vegetables. She divides the food evenly, and leaves his share on the back porch. When he needs drinking water, he sets out a can and she fills it up at the brook. She also brings groceries from the store. At sunset, after the second milking, she goes back to the cave, always by way of the road and the store.