This schedule was fixed long back. The slack given was sufficient as it took numerous looplines at intermediate stations in KZJ-SC section to OT goods rakes. But intro of PNBE-SC and increasing goods traffic has thrown its schedule into haywire.
I had numerous journeys 5-6 years ago wherein it did KZJ-SC in 2 hrs even after taking numerous looplines just due to the sheer acceleration of WAP-7.