The elegant BL navigation works with the target air line direction, quantified acc. to the Munich Orientation Convention:

m12 = from start point to north.

With this, the start point will always be behind, you'll always go outwards. If the local situation forces a deviation to "later" or to "earlier", so you'll automatically correct this whenever possible. The picture right hand shows the following situation:

The BL is m10. The way forces to go in direction m11 (too late). The next crossing allows to correct this, but in direction m8 (too early), the next way in direction m12 and so on. As you can see, the BL is a kind of WatchAngel which always will hinder to loose orientation. 

On the Points of Decision, you only need to know the north direction. The quantified BL will be a kind of WatchAngel© which always will guide you to the right direction.