Did you ever note that when intelligent engineers talk about designs (or quite generally when intelligent people talk about consequential decisions they took), they talk about their goals, about the alternatives they had, about what they knew about the properties of these alternatives and how these evaluated with their goals, about which alternatives they chose in the end and how they addressed the inevitable difficulties they encountered?

For me, this is quite a very telling sign of intelligence in individuals. And truly good engineering organizations do collect and treasure that knowledge - it is path-dependent and you cannot quickly and fully reproduce it when it is lost. And more importantly, some fundamental reasons for your decisions and designs might change, and you might have to revise them. Good decisions also have a quality of stability which is that the route taken does not change dramatically when an external factor changes a little.

So and now compare that to when you let automatically plan a route through a dense, complex suburban train network, by using a routing app. The route you get will likely be the fastest one, with the implicit assumption that this is what you of course want - but any small hiccup or delay in the transport network can well make it the slowest option.