The laying direction of straight planks influences where the eye is drawn. Planks laid lengthwise emphasise depth and make a room appear longer. They also enhance sightlines towards architectural features such as large windows or views of the outdoors.
When planks are laid across the room, the emphasis shifts towards width. This can make a long, narrow space feel more balanced. The ideal direction therefore depends not only on the shape of the room, but also on which architectural features you want to highlight.