Necessarily cut along
They mark up boards in such a way as not to adjust the boards again in the process of laying to each other.
Before the direct installation of the boards on the lags, they are necessarily cut along the entire length, the edges should be cut off only exactly at an angle of 90 degrees on the square used - this is done for the most accurate connection (all the cracks) of the two boards, which are located clearly one along one line.