Leading lines - my view on this "rule".
The rules of photography. There are many. Leading lines is one of them. The leading lines draw you into the photograph. Like in this image where the ropes attached to the boat do just that.
i quite like this shot taken one cloudy day in St Ives, Cornwall.
This is not a bad rule in my opinion.
Another important rule to remember. Blue sky can be boring. Indifferent to poor weather can make for much more interesting images!
We must not forget of course that you need to learn the rules of photography, then learn when and how to break them!