The Zurich S-Bahn network runs 2 - 4 trains per hour, depending on the route and is very successful. It complements trams (streetcars) and trolley buses in the

The Zurich S-Bahn network runs 2 - 4 trains per hour, depending on the route and is very successful. It complements trams (streetcars) and trolley buses in the larger cities - Zurich and Winterthur - which run in 6 - 10 (maybe 15 in Winterthur) intervals. It further connects to a rural network of buses that serve literally every tiny village in the Canton and are timed to connect with S-Bahn trains. The whole system is very successful and utterly useful with those frequencies. Arguably, the city of Zurich runs one of the best public transportation networks worldwide. You don't need a 3 - 4 minute interval if you're not connecting Tokyo with Osaka, or inner city Paris. What you need is a well designed network, with guaranteed connectivity and predictable travel times with a simple ticketing system (independent of mode of transportation) and maybe not the fetish that it needs to be financed by ridership alone.