As a traveller RSA doesn't make any difference nor the IR gets any benefit as both are day trains running in same direction. IR is a transport operator and they need to balance rake management, wear and tear, maintainance schedule. Kovai has less turnaround time or just 5 hrs-6 hrs in CDO while Brindavan has more time for PM of 8 hrs every 4 days and having RSA both of the rakes travel equal km on an avg per month without compromise on mainatainance.