The running time has drastically improved in the Mumbai-Itarsi section, as you have seen from the runs of 22221/22222. Unfortunately, the reverse is true for Jhansi-Nizamuddin. Though the MPS has gone up to 160kmph (from 140) in the last 24 years, the running times have actually increased, presumably due to much more traffic. For example, Gatimaan takes 4 hrs 25 mts from NZM to JHS with 160 MPS (and two halts) whereas my TVC Raj took just 4 hrs 15 mts for the same section back in 1995 (with one unscheduled halt).