Connecting a pitline at both ends is far more effective for shunting.
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Take this itself - say that Mumbai train comes to PF and then needs to be brought to the pitline. So they will have to attach a loco on the other end and reverse it to the pitline. Same loco or another one.
If connected, then the same loco can bring...
more... the rake to the pitline.
Shunting locos in the available lines and reversing the rake to the pitline is a major headache at big stations like YPR . That delays pushing the rake out of the PF and clearing the PF for other trains.