Breaking 1 block per layer reveals 4 blocks around it. 1 block for 4: 400% performance. (This method is the best.)
Breaking 2 blocks per layer reveals 6 blocks around. 2 blocks for 6: 300% performance. (This is a 2x1 branchmine shaft for comparison with the above method.)
But this is only useful if you are looking for caves and have a good way of getting back up (teleportation).
This is the pattern (gray lines indicate block borders/edges):
- Mining straight down with 100% coverage 1 zoomed.png (636 Bytes) Viewed 5008 times
This is how it tiles infinitely:
- Mining straight down with 100% coverage 1 tiled zoomed.png (13.29 KiB) Viewed 6294 times
And some more images:
Spoiler:
