Comment by bashkiddie

Munich is a counter example: It has many lines passing through (almost) 11 stations. They run at maximum speed of 40 trains per hour. It is a traditional block signal system with each block being shorter than a train - so they can run trains packed into tighter space. Each train opens left and right doors simultaneously so people can board and exit at the same time. Boarding still takes time. It is overcrowded at rushhour and brakes down regularily (a train being at a station for too long blocks all proceeding trains). And at Oktoberfest time, the stations are soo crowded that boarding takes longer.

Munich is planning on building a second subway route. It just does not have the money nor the space to build one. There has been discussion on building a second tunnel below the first, or on enabling the common train system for overflow by suburban trains -- by installing more signals to run more tightly packed.