I’m actually not so sure that it cuts commute time. What I am sure is it shows a lower estimate time up front, but at least in my case that estimate is mostly wrong. Plain Google Maps seems to be pretty spot on. Apple overestimates by a minute or two to give you a bit of a buffer, maybe. Waze underestimates by quite a bit and seems to pick the most obscure roads possible even when using the more common ones is not going to take any more time.