But you cannot compare a jammu rajdhani punctuality with other gang of rajdhani's.
hwh raj/sdah raj/dbrt/bbs/pnbe raj all run on a very congested and high traffice route and are bound to be late most of time.
bct raj/ak raj/mas/sc/tvc/sbc raj run on some what less congestion than the ndls-cnb-mgs section. Hence a bit punctual.
Jammu raj and ADI raj run on very less congested...
more... route hence have high chances of arriving on time.