@TchnclFl: my impression is that most of the work is proper placement of the parts. Once this is done the rest is comparatively simple. Even then the autorouter just does not seem to get it. Maybe I do not fully understand how to tweak it but for my boards it always creates poor layout. Obviously the autorouter just can not know that some signals should be closer together, other may need wider traces and so on.
Udo