From what I've heard of Switzerland, the real key is the trains being exactly on time. Once you can guarantee that, it's easy to set a connection at exactly 4

From what I've heard of Switzerland, the real key is the trains being exactly on time. Once you can guarantee that, it's easy to set a connection at exactly 4 minutes or something. OTOH, if your train arrival time is +/- 3 minutes, your connections are going to be too tight or excessive most of the time.