Classic example here..
A traditional SF with 16 -18 halts between UDZ AII takes 5 mins less than VB with less than half the stoppages.
VB gets benefit from quick Accleration and deceleration
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Talking abt single line section check Goa VB in Non Monsoons. Avg is way more than other trains and that too with more traffic load. In Monsoons the MPS is 90 ans still VB is giving 75 avg in sections.
I feel that AII UDZ AII can be dusted in 4 hrs 10 mins flat in one direction.
Also AII DEC VB covers AII JP in 1 hr 30 mins but UDZ VB is given 1 hr 55 mins.. So effectively this VB has end -slack is more than 2 sections
With proper slotting, 30 mins can be further cut from TT of this VB.