If the task is to create fastest route between German cities avoiding current and future traffic and also avoid road closures. How would you use your brain to solve it in reasonable time?
In the area where I live traffic planners have shored up all the inefficiencies that led to those apps saving you time in the past. Road diets. Right turn only out of side streets with a hardened median preventing a left or straight route. Speed bumps. Downright punitive light cycle timing (I’ve seen almost 5 minutes before). You often fare far worse in fact taking those labyrinthine google maps/waze circuits through these residential side streets and shed time just sticking on the major arterials and highways.
So you'll pick the major highways and follow any detour signage like you would have in the old days.