With this picture of a field the road as the leading line cuts straight across. In theory is should not work well as an image but to me it is pleasing and balanced. I think that it is the other shapes in the fields (the plough lines and the tractor tracks) that slow the eye down as it scans across. Also the diagonals are at such an angle as that makes the whole image seem balanced enhanced by the almost monochromatic abstract feel. You may well have to look twice or more to realise it is a field.
The next image uses the intersection of the two roads to break the lines. Whichever way you look the eye is drawn to the crossroads which follows the Rule of Thirds for its placing. Again the simplicity of colour abstracts everything out but a hint of reality returns with the partially ploughed field next to the road.
The strong diagonal field boundary cuts across at a similar angle to the first picture but this time it is intersected by to other fields one of which at a strange and jarring angle. In theory it should not work because of one inharmonious angle. But this is where with the colours is the images strength. This line actually stops it from being totally balance and your eye being lead out the image.
Overall I would agree with the statement that you eye travel fast along the leading line and straight out the picture and some form of ‘stop’ is required to slow things down, even though it could be just a change in colour as in the lettuce earlier.
I suppose like all techniques lines must not be overused. If every picture had strong leading lines I think the eye would soon become accustomed to this and then start to find the image uninteresting and the power of how it can be used to make a great picture diminish.