Why you are comparing with ICHHA- BZA with ICHHA-GNT ??
Compare between time taken by IPM-BZA by both trains. Else add another 1 hr 30 min for PURI-TPTY exp for GNT travel from BZA.
In that case PURI-TPTY takes around 17 hrs which is again 2 hrs slower than this normal special also.