Minecraft wiki entry for Mining, associated text: With a shaft of 4×4 or more, two staircases on opposite sides of the shaft going in the same clockwise direction can be added, allowing horizontal 'satellite shafts' to be added on each flight of stairs on opposite sides if the shaft, allowing for extremely efficient and exhaustive mining, and in shafts of 5×5 or more, a staircase can be added on every side of the shaft for an even more productive mine.