Having just read a bit about what the heraldry rules are and the purpose they serve, it strikes me as very similar to the design ideas of transit maps in modern

Having just read a bit about what the heraldry rules are and the purpose they serve, it strikes me as very similar to the design ideas of transit maps in modern times. You want the lines to be easily distinguishable, certain colors shouldn't run side by side (so the conventional wisdom says), you choose only from a minimalist simple pallet. In most places, the maps are diagrammatic, the lines can be arranged in any way so long as they connect the right stations in the right order. Convergent evolution.