Thickness of line for SVG file

Line thickness, or rather stroke width from Inkscape, is irrelevant in determining number of passes or filled area.

In essence, lines are perceived to be infinitely thin. It’s the path that’s relevant, not the stroke width.

If you are getting double the number of passes I suspect what’s actually happening is that instead of a single line you actually have a very thin rectangle and it’s burning both side of that thin rectangular line.