SBC LTT with RSA LTT UBL is definitely possible. UBL train terminal was shifted to DR only recently.
Onward SBC LTT : SBC 2200 UBL 0500 LTT 1900. RSA LTT DEP 2030 UBL 1030.
Return UBL LTT : Dep UBL 1600 LTT ARR 0630. RSA LTT DEP 0830 UBL 2230 SBC 0530.
With Slight readjustment, it is possible. Another advantage would...
more... be that no rake idling at Mumbai.
When Nagercoil Mumbai can turnaround in 1-1/2 hours, why not a Bangalore Mumbai train turnaround in 2-3 hours?