I wouldn't say schedules are useless, they are actually pretty helpful to humans (e.g. the bus is scheduled for 5:13, but in rush hour that means it will probably be there closer to 5:20). Tracking is clearly more helpful if available, however.
As an aside, thanks to the GP for showing me OneBusAway, it's exactly what I've been looking for!
A bus 7 minutes late during rush hour, that's funny.
During rush hour, bus arrival times are randomly distributed between 7 minutes late and "so late that you could say the next bus was 1 minutes early" (Any later and you just can't prove whether the bus that arrived was 30 minutes late, or the previous bus was abducted by aliens)
Specifically, Google Maps tells me that the 2 bus is arriving at 10:30AM. OneBusAway tells me that it's running 8 minutes late and will arrive at 10:38AM.
Schedules are not useless, but they are alot easier. While alot of agencies are publishing their schedule information in GTFS, very few agencies are publishing their real-time information in the GTFS-realtime format.
It depends on the transit system. MUNI (San Francisco's transit system) buses are horribly off schedule during rush hours, to the point where if you rely on them, you often end up waiting longer than if you randomly show up at your stop. Tracking is really the only reliable method for this. Compare this to BART, where the trains are almost always on time, or within 1 minute of the schedule.
