Vikramshila takes around 5 hours to cover MGS CNB
Poorva (via BSB) takes 6 hours 20 minutes to cover the same , even if 1 hour is added for Phaphamau to Unnao or 2 it comes to 8 hours 30 minutes which is acceptable provided it runs on time.
10 hours on time run in a line with less traffic is also acceptable atleast the train will arrive when it's supposed to