By "directions" I don't mean real-time spoken directions -- I use that mostly when driving solo to somewhere unfamiliar, and have never used it for public transit -- but just looking up in advance the possible routes and schedules to get from X to Y. That tells Google Maps that you're interested in going from X to Y by public transit. I actually do that fairly often, as NYC has enough different subway lines, with local/express distinctions and intermittent track closures, that it's not always obvious which stop of which line is the best for your trip right now.