It is not like this.... IR makes many trains like Kolkata - Agra Cantt Superfast Express via Farrukhabad and Sealdah Rajdhani Express skip Allahabad Jn. Premium Trains are believed to be 5 Stoppage Trains and this is why
Sealdah - Katra Premium Express will also miss out on Dhanbad and Gaya as Commercial Stoppages and that doesn't mean that Grand Chord Stations can't provide good patronage to Superfast Trains.... so kindly don't take Premium Trains to your heart <3