Feeling bored in the Train - talk to a RailFan. You'll WISH the train gets late.

Greetings everyone. I have a technical question, not sure if "Rail Fanning" is the correct category to use though...
Banker locomotives are used on gradients for safety and operational reasons. Amongst operational reasons, one is to help the leading loco up a gradient at a certain speed, which would otherwise not have been possible.
What if, a banker locomotive is attached to a train that is running on a flat terrain, say on the Delhi to Kanpur track. Will this locomotive not be able to help a train accelerate faster as it starts...
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from a station? I.e. the top speed can be reached in shorter duration of time. Similar performance when stopping, the train could stop over a relatively shorter distance. Doing this could increase the average speed of the train, especially passenger trains that have to start and stop often. Also freight trains could see improvements.
Can someone give technical gyan on why this is not possible, or not done by the Railways? Thank you.