I did a little test today. Instead of taking I-75 from Lexington to Cincinnati, I decided to take US-25, a 2-lane road roughly parallel to the interstate. Obviously 75 is going to be the preferred route, since it's faster and shorter, so I went to settings and set "avoid highways" to ON.
It works, if you want to avoid highways. It works AMAZINGLY well.
But freeways, it seems, aren't highways.
As I drove along New Circle Rd (a minor highway) a few miles before my turn onto 25 (also a minor highway), Waze desperately tried to get me to 75 as fast as possible without using any highway segments. It kept recalculating routes through neighborhoods, parking lots, ANY white segments to get me to the nearest on-ramp to 75. After I got onto 25, it kept it up, even when I was nowhere near an exit; it seemed much more determined to get me off of that minor highway than to get me anywhere near Cincinnati.
So whatever the intent was for this option, I don't think it's working.
However, I don't recommend scrapping it entirely. It has tremendous potential as a diagnostic tool for TTS pronunciation, since it will announce the name of EVERY SIDE ROAD YOU PASS.
"Turn left onto Ironworks Rd"....<recalculating>..."Turn right onto Lisle Rd"...<recalculating>..."Turn left onto Coleman Ln"...et cetera ad infinitum ad insaniam.
Eventually I had to switch it off because all the recalculation was interfering with candy distribution.

