Traffic and accidents might push you into different routes, especially if you have major decision points like which route you take around some geographic feature. When I drive in Los Angeles decades back even people who’d been driving there for ages wanted traffic reports to pick between roughly equivalent freeways because almost inevitably one of them would have much worse congestion due to an accident and you could save 20+ minutes.
Distances in LA aren't measured in miles, they're measured in time -- and the distance between two points changes based on time of day, direction, and events like sportsball or presidential visits.
Knowing where to switch between freeways and surface streets, and what route to take in what conditions, can cut half off the driving time.
Some examples of varying conditions from my personal history, even with optimal routing:
Commute to work: 22 minutes. Commute home: 1h 16min.
Go visit a friend: 45 minutes. Come back home at night: 16 minutes.
> Knowing where to switch between freeways and surface streets, and what route to take in what conditions, can cut half off the driving time.
Yes - I remember as a kid learning how to read maps and noticing my dad's face when I was like "These cities are only 10 miles apart. Why does it take an hour to get to grandfather's?".
The surface streets are an especially interesting blindspot a lot of drivers have. There was a period around the turn of the century where I was commuting between Santa Ana and Garden Grove and freeway traffic was generally manageable early in the morning but on the trip home it was often better to cruise down the surface streets where the lights were timed around 20mph than to sit in stop-and-go traffic on 405 or 55/5.
Driving in the London suburbs, I know how to get most places I want to go. In fact I usually know several different routes that are roughly similar in travel time. Google maps is excellent for telling me which one of those routes is least congested right now. So I'm not really using it for navigation, but for congestion information. It very rarely suggests a route I don't know, but I use it all the time anyway.