Unless I'm really trying to focus on something more technical or a trick I don't have locked or now how to do, I rarely even notice setting-up. I know I do the cig snuff to a degree, but luckily it hasn't been super obnoxious or maddening.
I kinda just put my feet where the trick has worked before and send it (for lack of a better term). If it didn't work, evaluate and adjust. Though, I don't really skate all that tech, so my foot placement is not always super critical.
On the flipside, setting up for something out of my bag, I get hyper focused on foot placement. Fighting for 360 flips is my most recent example. Inner dialogue: "okay, back foot heavy in the scoop of the pocket - oops a bit deeper... okay, front foot nice and light hanging a bit heelside, shoulders square and over the board, weight centered over the back truck, okay... SCOOP" and fling it like I don't know wtf.
TLDR: muscle memory, I guess