The suggestions above that refer to spliting large planks for various needs in the early times was necessitated by the need for flooring in barns and other areas that required stout carrying capabilities. These large planks can be seen as surviving examples and no doubt were split out at that time.
One idea that I do have pertaining to the splitting of large planks was that the tree was split right through the centre giving you (2) halves to work with, and then quartered or split in different ways, much as the splitting of rails for fencing. this would result inno hewn timber, and the tree in question would be for splitting only. Splitting would be carried out with smaller dimension timber, and would no doubt be easier to work with.