I mean, even applied voice 'models' suck for this.
For some godawful reason, Apple Maps voice directions assume that you also understand what it omits. So if it says "turn right in 500 meters" "250 meters" and then you stop at an intersection after 150 meters and it says "turn right", it expects you to understand that it doesn't mean the immediate right at the intersection, but the next one [because you still haven't driven the full 250m]. It is nuts and I have no clue how that has ever gotten past testing.
What it should do is say nothing until I have to turn, or say "turn right in 100 meters" "turn right".
This is one thing Waze I think seems to do better than the competition. And they have a ton of different voices.
They also clearly show which voices can do street names (which is hugely helpful). For some reason the Australian and British accented voices feel more polite than the Americans