The importance of frequent transit service

I was flying back into the SFO airport yesterday, and since I live in the South Bay, I needed to find some form of transportation to get me home from the airport. Fortunately, there is a BART station right at the airport, and I live quite close to a Caltrain station. I even had my Translink card with me. Unfortunately, I missed a BART train by 30 seconds. Since BART only runs every 20 minutes, that means that I would miss the connection to Caltrain, which runs once an hour, which would mean that I would get home an hour later than if I had run slightly faster to catch that train. Instead, I took a SuperShuttle, which, with waiting, actually got me home almost exactly when I would have gotten home had I not missed that train, but at considerably greater cos ($40 instead of $8.25). In this case, the reason I did not take transit was not transit's speed, and that is given that a local Caltrain is pretty slow and waiting for the connection takes time too. Rather, it is end to end travel time, which is a function of both travel speed and waiting time, and the latter is largely determined by frequency. And it's a virtuous cycle: increased frequency can increase ridership, and I suspect that the Moscow Metro would not be as popular if headways at 10:30 pm were 20 minutes instead of 4.