What's the most land trade routes you usually have simultaneously, for leaders with no specific land or sea trade bonus? (Ignoring Petra.) For example, vote for "3-4" if you usually have at most 3 caravans active together at any point in the game. You might replace them with new caravans after they die, shift their destinations, or replace them with cargo ships later. Still vote for 3 if the most you ever have going concurrently is 3.