Minecraft wiki entry for Mining, associated text: There is a tradeoff between the spacing chosen between each branch of the mine. A spacing of 2 blocks per branch means that players will end up exposing almost every block, but at the cost of a lot of work. A spacing of 5 blocks per branch will give them a wider area covered but there is the possibility of missing some blobs, especially diamond or lapis lazuli which can appear in blobs of less than 4 blocks. Using the diagram titled "More compact 3-Space branch mine" (open the "Offsetting mine levels" collapsible to see it) leaves no ores hidden, however requires them mine more stone. It is recommended to use this method if they don't mind mining a bit extra and really need the gold, redstone, diamond, iron, and coal.