Minecraft wiki entry for Mining, associated text: A straight staircase heads down, but also over. This may or may not be useful — with a map, the player might learn about more of the surface they are going ‘’under’’, but if they need to dig their way back up a different way, they may come out in unknown territory. Also, a long staircase from their base may take them out of chunk-update range from their base, or at least far enough out that further exploration will take them out of range. Then their crops won't grow and so forth while they are mining. All of these can be 1, 2, or even 3 blocks wide.