An understanding of how the bevel rotation angles are defined will make it easier for you to manipulate them to get the result you are after. The illustration below shows how they are defined.
In the above example the bevel tool is following tangentially so that the bevel angle is normal to the path. If we turn off tangential following and instead keep it at 180º for example, we can obtain the result shown below in one simple cut, where previously it may have required corner loops to reposition the bevel.
In the following tutorial we will use this technique to cut a hole in a plate to allow a pipe to pass through at a 45º angle.