Very cool, if true

I'm defining N to my own satisfaction, from my experience waiting for buses. Also, it's <20, not =20, so 15 isn't far off.

My experience with MUNI, if you mean the San Francisco bus system, is that if the bus is delayed, two will come in short order, and if the first is sardines, the second will be one of those crisps packages that's mostly air.

Also, these days many of the MUNI stops have electronic displays giving estimates times until the next two buses on each route that stops there; and it's also possible to get this info on a smartphone app.