Off highway, I leave O/D off.
With the frequent changes in speed limits from 25mph to 45mph, it would constantly be shifting up and down, which results in a lot of time with the torque converter unlocked.
O/D off around town keeps the torque converter locked the most time, and the rpm's around 1,500 to 2,000.

 

I thought the torque converter doesn't lock up until it's in OD and holding a steady pace for a little while. Unlocks when it senses throttle or load? So if OD is off it would stay unlocked....

 

It locks up just fine in 3rd.