Sunday run is important for any intercity type train for people to return to work and resume office from Monday. Someone very clever knew this and chose to give Sun slot to 21893/94 because 10 hours on weekend will be a disaster but anyway 21894 is going to see that day on Monday.
Despite, what has happened 20893/94 will be the most profitable one with 4 days only. SER will realise soon what it has done.