Industrial trains should be able to choose (many modern loaders can go from front to back as well as from side to side, this was invented specifically to avoid the problem of trains having to wait for another train loading at the reserved track – staying flexible during adjustments).
Also I just read this (Dutch):
Which convinces me passenger trains should also be able to choose lanes at a station.
Why to you think large stations have dynamic boards on which the times and platform numbers are shown. It is totally realistic to choose ‘available’ platforms rather than having a fixed one.