Traffic reports. Saved me hours a month (usually 1-2 hours each time) when I got rerouted around a bad accident on my primary route home at my previous job. It was the main highway connecting the area near my office to the town I actually lived in. When there was an accident, it was 30-90 minutes of being stuck without moving, depending on if there were serious injuries/fatalities (versus a fender bender). With a notification before I left the office [0] I could choose the longer but not backed up route.

[0] I usually left halfway through rush hour, most accidents seemed to occur just before I left but I never crunched the numbers so just an observation.

I know 5 or 6 given paths. Which one is fastest depends on all sorts of things. Is there traffic? Has an accident on the highway brought things to a standstill? Is going North around the lake slow enough that the toll lanes are worth it?

Even when I know where I'm going, it's very useful to have an accurate ETA. If I get a call, I can tell someone quite precisely when I expect to arrive.