I gave u a similar example. There is no direct train till date from Kharagpur to Amritsar. Passengers have to travel 2 to 2.5 hrs to HWH or 2 hrs to TATA or 3 to 3.5 hrs to SDAH to catch train to Amritsar. Kharagpur is many times bigger station than Bhadrak or Cuttack. So, in IR it is not necessary that every station will have direct connectivity to every other station.
SER will not run any train via long route from SRC to CSMT via Bhadrak whdn shortest route via TATA is available. You can tweet to ECOR for a train from BBS to CSMT via BHC, HIJ, TATA route.