It's called strip/branch mining (https://minecraft.fandom.com/wiki/Tutorials/Mining#Branch_Mining https://minecraft.fandom.com/wiki/Tutorials/Mining#Branch_Mi..

It's called strip/branch mining (https://minecraft.fandom.com/wiki/Tutorials/Mining#Branch_Mining https://minecraft.fandom.com/wiki/Tutorials/Mining#Branch_Mi...) by players. Everyone (including children) learns this method over time, be it by checking tutorials online, reading a wiki, or just naturally due to how simple and efficient it is. You just had to mine straight down to y 8/13 (this changed in the new patch), make a long corridor and then just branch out of that corridor in lines.