Divided roads

Because I do not have avoidances set to exclude U-turns - my GPS will look for next opportunity to get into the opposite lanes accordingly, either by a turn left opportunity, a U-Turn, a set of lights or a cloverleaf type exit on the highway !

I believe that the route to the end point is based on fastest or shortest, whichever you had set up as your preference. The nüvi maps seem to be fairly legal savvy but it is always prudent to pay attention to the signs that my prohibit a left or U-turn. I can't recall ever having Jack tell me to do something that could get me a ticket, but there is always that chance.

If you are on an expressway, it will have you exit so that you can crossover and continue to the destination. On other divided roads it will look for a crossover and offer a U-turn unless as MrKenFL pointed out where he has his U-turn choice disabled. In that case it will try to find the best left turn to get you there.

It's rare, but it happened to me once, only I was paying attention and ignored Jack. My destination was after a left turn at a traffic signal on a divided street but Jack wanted me to turn right and then make a U-turn! I recreated that route a day later and he did it correctly the 2nd time so he must have learned his lesson.

I believe FedX or UPS uses software that avoids left turns when plotting delivery routes, but I'm not aware of any consumer GPRs that work that way.