When multiple vehicles serve overlapping areas, routes can end up long and sprawling, with vehicles criss-crossing each other's paths. Planners may prefer routes that stay geographically compact, where each vehicle's visits are clustered in one area rather than spread across the map, even if a more spread-out route would be marginally more optimal by travel time alone.

This is a soft preference: compact, non-intersecting routes improve driver experience and make plans easier to understand and trust at a glance.

One possible approach: penalize each vehicle shift based on the maximum travel time between any two visits assigned to it, encouraging tighter geographic clustering.