Yes....Due to Food court and BEST facilities are present on Pf 4 ,plus srew running room and RPF post/Resting room is also present on that Pf 2-4 area. Thats the reason why they give Rajdhani Pf 4 maximum time.
Whereas Puru , Neelachal , Nandankanan gets Pf 5 or 6 regularly...