You know... we should optimize the IDL with a graph partitioning algorithm. We can measure inconvenience by the number of times any human's life trajectory passes the IDL. That's impossible to measure, so let's use recorded passenger airline / boat transportation numbers as a proxy. That also quantizes our graph into distinct origin and destination nodes. We penalize any graph edge that transits the IDL. Then we just find the min-cut of that graph, and draw the new IDL across the cut. That still leaves us lee-way about where to cross each edge in the cut, so we can apply aesthetic heuristics to try to draw a maximally straight line, or one most aligned with meridians. Then this will no longer be arbitrary.