U mean via SLN, trains are quite on-time??? Its a myth, fashion & legend to tag train diversion via SLN-MB to rectify its late run!!
Kindly check the ARR/DEP history of Himgiri, Shramjeevi, Sadbhawna etc!!
& even the Rajdhani u mentioned on this route is among the slowest Raj, slightly faster then SF!!
Via MB will make addition of some 1.5-2 hrs in its TT which lead to hardly 1 hr saving, as compared to its late run while 1.5 hrs wastage, with its regular run...no much big deal!!