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.
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.
