[eterevsky]

A train usually stops at the station for only around a minute, so there is no time to change to another platform unless another train arrives later.

There are some trains that stop at the big train station for a longer period of time, so it might theoretically be possible. I live in Switzerland and I don't remember ever changing trains like that (though maybe I just didn't notice).

[lolc]

Intercity trains in Switzerland do stop for longer periods. This is a basic feature of the network to facilitate transfers.