Hi Amaury,

This distance is applied to the more dense layers in the graph. Their neighbors in adjacent sparse layers are centered above or below them to make links shorter as shown here:


If you need to use the same distance in all layers, you can loop over the nodes after arranging the diagram and adjust their Bounds horizontally, but the result will be uglier in most cases, e.g. something like this but on a larger scale:


Also if there are several unconnected subgraphs, the closest nodes in two adjacent subgraphs will be at Layout.Margins distance from each other instead of NodeDistance.

I hope that helps,
Stoyan