It is possible for train A and train B to arrive at the same time, and depart at the same time, allowing convenient transfers in both directions. From my brief experience on Swiss railways, I found this arrangement to be quite common.
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).
