I find my foot position reasonably consistent, front foot at a 35 degree angle (ish), with my toes covering 3 of the 4 front bolts.
What i do have to change and tweak deck to deck, is the direction of my flick, some decks i flick out to the side more, and some more straight up the board into the nose. Also have to change my back foot position if i'm skating a short tail vs a longer tail.
I will also, without fail, primo about 1 in every 15-20 kickflips...no matter how many times I session them, or what i change up. The rest of the time i've got a reasonably clean and consistent kickflip. Tend to primo regular ones more than fakie.