Not needed at all. Primer is for Bare Drywall and for mud patches. Imo if your going to prime to help a color cover in 2 coats just do 1 more coat of finish. Tinted primer is helpful for a color change if your going from say white to bright yellow. Black to white. More extensive color changes, other than that no need at all. A good quality paint will cover in 2 coats and you will be fine.