Yes trains are deliberately delayed to utilise slack and to avoid early arrival at major station as they don't want them to occupy pf for longtime crawlers like circar,Bokaro other examples they have huge slacks to utilise that they make way for other trains,bza division want circar to be at coa by 10am even if it can arrive coa by 8pm with same dep from cgl so to avoid early arrival its get oted by every train till slo from gdr
Same with Bokaro it should reach mas on time again the huge slack will make it reach mas on time so they delay it between dvd and gdr