I should have mentioned the bicycle setting in my link; Panama and the canal seem like a good example to illustrate how the shape of isochrones can change based

I should have mentioned the bicycle setting in my link; Panama and the canal seem like a good example to illustrate how the shape of isochrones can change based on geographic and transport conditions (most cities will probably result in fairly concentric circles for walking, cycling and driving). Anyway, glad to hear that the routing takes those road usage restrictions into consideration :)