Hi Charlie,
You won’t need that very often, but it’s good to know, that you can do it.
The main time when I used it, I think, is when using the Build Modifier on a Curve (for instance, when simulating writing text). If you find, after having spend a long time drawing the Curve and then find it’s building back to front, Switching the Direction of the Curve is about the only way to fix that, as far as I know.
When Animating an Object along a Path, you can use it, but then you could also just reverse the Animation (swap Keyframes).
In for instance this Course: https://cgcookie.com/courses/bcity-building-a-procedural-city-generator-with-geometry-nodes
the direction of Curves sometimes needed to be switched, but that was done inside Geometry Nodes.
