Okay, I thought I’d post a workaround that I have discovered, in case anyone has had similar issues.
In order to get around the fact that the ‘Wiggle Paths’ effect has a diminishing effect over the length of the line, I have worked out a way of repeating the line so as to create a very long wiggly line over which the effect is just as strong as if it were a short line.
I applied the Wiggle Path effect to my line as normal. In the drop down ‘Add’ menu within the shape layer, I then added a ‘Repeater’ and discovered I could create as many versions of this wiggled line as I liked. Fiddling around with the parameters inside the repeater, I could make each repeated line have a scale of (-100%,100%) of the previous line, and adjust the position, so that they formed an unbroken wiggly line (effectively looping the wiggle). This means I avoided the necessity of having a gigantic precomp in order to create the parallax effect over my array of lines. I hope this might help someone else along the way.
David