If SR run PDY MRJ and TEN MRJ trains at a different faster slot via RU, GTL, UBL, Chalukya slot can be used for Mumbai Bangalore SF.
Now, no end to end traveler would prefer this. Better options for Pondy passengers are biweekly CSMT NCJ via VM, Weekly KIK LTT and weekly LTT MDU. For Madurai, Thirunelveli passengers, you have CSMT NCJ in convenient timings.
The wrong decision of extension can be reversed.