How Did We Get Here? The History of 롤경작 Told Through Tweets
http://devinyrhm961.trexgame.net/lol-yugseong-all-the-stats-facts-and-data-you-ll-ever-need-to-know
For the reason that runecrafters can only carry 23-27 essences at any given time, they don't seem to be ready to build up greatly runecrafting knowledge very quickly.