Board Thread:General Mod Discussion/@comment-27752412-20160221173323/@comment-27219153-20160222032957

Thorin Stonehelm wrote: ...instead of 6 blocks between tunnels use 2... The reason I use a 6 blocks in between is so that the veins I mine don't overlap. For instance, I find several connected ore veins that, together, are 5 blocks wide. Using 2 block spacing, I would discover these on at least 2, possibly 3, of the tunnels, whereas with 6 block I would only see these ores once. Mining with wider spacing minimizes the risk of this happening.

One could make the argument that mining with wider spacing causes you to miss ores (which it does), but unless you are limited on space, there is nothing wrong with missing ores. So if you are playing on singleplayer, or on a low population server, you probably aren't going to run out of mining area using wider spacing. However, playing on a larger population server could result in there being limited area for you to mine, in which case you should use smaller spacing.

I also want to note that because of the way ore veins spawn in minecraft, it is almost impossible to miss ores in a 3 block spacing. Using 3 block spacing instead of 2 yields almost almost identical results, while only taking 2/3 of the time. This youtube video explains this very well.