I for one use the drywall primer and have had great luck with it. I do put on two light coats before the finish coat. Many years ago when there was no such thing as primer, flat paint was used for that purpose. Flat paint has that rough texture that is great for other stuff to adhere to. That is why flat is NOT washable. Under a microscope flat looks like the grandcanyon.
I really like all the Zinzer products for primer use, then I will go to the Kilz.
I think you are on the right path with your program your using.