A few degrees of additional rotation leaves a few more external cells, but better orients the grid such that rows are perpendicular to the stream and columns oriented toward the lake which is closer to the anticipated major axes of flow. If the materials were anisotropic, we would want to orient the grid to coincide with the major axes of the hydraulic conductivity tensor.

For your convenience the previous grid, that showed how more inactive cells would occur if the grid was reoriented, is shown below.