Most Smetsson cutting boards are crafted with end grain. This means the wood fibers are oriented vertically in the cutting board. You know you're looking at an end grain cutting board, when you can see the growth rings of the wood at the cutting surface of the board. By contrast, most commercially available cutting boards are made of edge grain. Here the wood fibers are oriented horizontally and run parallel with the cutting surface.
If you compare the wood fibers of the cutting board with the bristles of a paintbrush, then cutting on a edge grain cutting board relates to cutting across the bristles. This results in damaging the fibers and over time bits and pieces of wood will break off and the cutting board will become slightly hollow in the middle.
Another result of cutting across the fibers is that the knife will become dull more quickly.
When end grain is used, the wood fibers are oriented vertically in the cutting board. On such a board, the knife cuts in between the fibers. This gives the wood almost “self healing properties”, because the wood fibers get pushed aside during cutting and come back to their original position after the knife has past. Resulting in a wood surface that remains almost undamaged, even after intensive use and many years of cutting. It is no coincidence that butcher blocks have been constructed from end grain wood for centuries.
Moreover, a knife will hold its sharp edge longer when used on an end grain cutting board, because the knife edge is being pulled in between the fibers instead of across.
If you're cutting on a long grain cutting board, you're damaging the wood and the knife.
The point of an end grain cutting board is to offer a neutral surface that doesn't get cut but rather moves out of the way.