Nuvi was purchased in spring of 2012. DH is the techno-geek in the family. I don't even try to keep up. I know he gets an email, pays some money, hooks it up to the computer for a bit, and says it is updated. That's about the extent of my knowledge about updating.
I'll dig deeper for the "most use/least use" option. I hadn't come across it when I was messing with it during the trip. I only saw a "avoid highways" option. There was also a custom option to tap the road on a map to avoid - tried that - tapped I-95 and it locked up calculating for 15 minutes until I just canceled the route and winged it on my own.