Yeah, LOCK. In good weather, I keep it in Auto or if I go into manual, I keep the indicator at the bottom green led or one above that.
I've got great snow tires and even then, I've got the DCCD wheel set to the highest yellow led before lock and set to Auto. That way, when it gets pretty bad, I can switch to manual and already be in a tight setting. If I need more traction, I just bump the wheel forward into LOCK. It's so slippery out there that even in LOCK, going straight, ~35-40mph, I can put my foot down and all four tires spin.