You are correct. Probably the frequency of other trains like Tambaram - Santragachi Antyodaya should be increased. Trichy - kolkata SF is also running 2 days since its inception in 1998, why not increase its frequency too? Rather than torture people utilize the available resources and give more comfort. According to time table, 22808 chennai central - santragachi runs weekly twice, 22826 chennai central - shalimar runs weekly once, now railway must answer why these 2 trains are not run daily when there is so much demand.