This happens with many SF trains they have stop only in one way basically seen in case of stations in city suburbs.While returning its given since people can alight from there and disperse to home.Also stop at Yelahanka would in midnight many won't prefer it so that also adds to it.
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One Example is 12701/Hussain Sagar SF while going from CSTM-HYB doesn't stop at DR inspite it being a important one,but the 12702 HYB-CSTM stops at DR so that public can get down and disperse to their homes.