You can‘t compare a train station like Zurich HB with an airport, where all passengers leave the plane at the same place/gate and the distances between gates, let alone terminals, are much, much bigger. In an IC train up to 400m long, your seating position whether at the front, end, or middle of it will have a much higher impact on the distance to whatever service located outside of the platform areas than the platform number itself (no services are available directly on any platform at Zurich HB)
E.g. if sitting at the very front of a train arriving at Zurich HB at one of the ground level platforms 3 - 18, the distance to the services located around the big departures display hanging from the ceiling at the end of the tracks would be basically the same for all those platforms.
Should you however leave the train at the opposite end, then all services located in the „Sihlpassage“ underpass (shopping/services area) would be approx. 3 minutes closer. Here again, regardless whether your train arrived at platform 8 or 11.