Sign at Collingwood

I saw this sign at Collingwood station. I have been taking the Hurstbridge line regularly for 5+ years at all different times of day/night and have never seen anything but a 6 car train. Is this sign needed or useful in any way? Am I missing its true purpose?

I saw this sign at Collingwood station. I have been taking the Hurstbridge line regularly for 5+ years at all different times of day/night and have never seen anything but a 6 car train. Is this sign needed or useful in any way? Am I missing its true purpose?