Eastern rail earning main root is howrah/sealdah to North east (guwahati/ new jalpaiguri,) to bihar (patna/ bhagalpur/ darbhnga/mujafarpur) , to north ( delhi). Onno route all loss train runs ... all slowest , flop trains running by ER so every year ER zone running in loss .
Slowest trains of ER:
Howrah-Amristsar exp -loss
Howrah-Gaya exp -loss
Sealdah-Delhi...
more...

upper india exp -loss
Sealdah-varanasi upper india -loss
Howrah-Katihar exp - average earning
Howrah-siuri -below average earning
Many other passenger trains r sdah division emu in loss increasing ER zone.
Eastern rail malda r asansol div i have no idea of slowest trains.
SER zone high income every year less slowest trains very few:
Slowest train in SER:
Shalimar-Kurla ltt exp - above average good earning
Santragachi-paradeep - not slowest train but huge loss
Santragachi-Ajmer exp -loss
Kharagpur-purulia intercity - not slowest train but loss
Jhargram-purulia intercity - below average earning
Howrah-barabil janashatabdi - not slowest train but average earning
Shalimar-Adra rajya rani exp - not slowest train but loss
Shalimar-bhojudih simlipal exp - loss
Santragachi-madras antodaya -loss
SE ranchi r chakdharpur i have no idea of slowest trains.
SE haldia emu line loss, kintu goods movement income huge
South line from howrah high income, west india line good income,
High income zone SER increase every year