TN,Dakshin,Kerala,KSK via KCG has good TAT so delays will be less harldy in worst case delays go only 12hrs
But AP,GT and KK exp has less TAT which results in more rescheduling as they undergo secondary maintenance for 6hrs at NDLS/NZM also
And Even Goa exp has less TAT at NZM but there is spare rake at VSG all the time so delays will be less at VSG