I think one key point why things are this way for CH, is that they decided to move to Takt scheduling (clock face scheduling) in the 70s. Integrated country-wide scheduling, makes doing those long term planning much easier.

(e.g. you know there's no point making some connection faster, because the lines still have to sync at 15m/30m/1h points. So you can focus on the places where you can go from a trip taking 40m to one taking 30m, because those are the one that will have a massive impact.

https://en.wikipedia.org/wiki/Clock-face_scheduling

(iirc that video covered it too: https://www.youtube.com/watch?v=8y9hGofgy9c )