Durontos to and from NDLS are too bad. But my experience in 2 other durontos has been quite good. HWH-Pune/CSTM and YPR durontos are quite punctual compared to durontos like 12273/74 and 12259/60.
Especially, the Durontos connecting NR to ER are worst in terms of punctuality. Solution is to either stop them or change their routes or schedules so that they can run smoothly without encounters with other important trains.