Sampoorna Kranti's slot is perfect.
It chases Magadh till Jeonathpur as mostly Magadh is overtaken just after DDU.
Secondly, Sampoorna Kranti runs after Patna Rajdhani and before rest Rajdhani gang, making it a High Priority train and it doesn't distrub prayagraj exp and humsafar.
Thirdly, Patna Rajdhani overtakes SK at DDU itself.
All...
more... Superfast Trains including Rajdhani, Garib rath are running in this slot only.
Like first Patna Rajdhani departs DDU and followed by Sampoorna Kranti, Dibrugarh Raj, Howrah raj, Sealdah Raj, Bhubaneswar Raj, Ranchi Raj and atlast BGP,JYG Garibrath, etc.
If sampoorna kranti is made to depart DDU first then it will surely be overtaken by Patna Rajdhani between DDU-PRYJ which will result in delay.
That's why Sampoorna Kranti arrives 30 - 35 min advance at DDU making a clear way for Patna Raj to Overtake it.
Moreover, sometimes Patna Rajdhani overtakes Sampoorna Kranti before DDU. That's why slack is provided to it.
And not even DDU, many trains have been providee with a slack at many big stations.