Then that's a poorly resourced and underused rapid transit system. A heavily used subway line can run trains every 3-5 min during rush hour (and on some lines,

Then that's a poorly resourced and underused rapid transit system. A heavily used subway line can run trains every 3-5 min during rush hour (and on some lines, ridership is high enough that they'd run them even more frequently if safety allowed); a bus route, every 2-3 min; and commuter rail every 10-15 min. Even at 3am, my nearest subway line runs trains 2-3 times per hour. Unfortunately, underutilized transit options are subject to a vicious cycle wherein it's impossible to justify running more frequent service for low ridership, and lack of frequent service suppresses ridership. Once you do have a strong public transit culture, it builds on itself and makes investment in frequency an obvious choice (not just for convenience but because you need more buses/trains to fit more passengers!)