Actually, you couldn't be more wrong. If one understands the core principles of centerline and veiws of maximum efficiency, then the main goal for SNT level thinking would be to stand your ground and deal with the attack as it comes (loi lau) without having to step. If you can do this and dont need to use footwork, you dont - ie you only move when you HAVE to. Example, if someone throws a punch but I can redirect it without footowork thru proper understanding of timing, structure, positional advantage and leverage, we only needed to change our OPPONENT's position. This is WC at it's most efficient and this is what SNT teaches us. Of course, not everything works like this in a perfect world, which is why we have CK
Because, if on a bridge has been made, you cannot deal with the energy on the bridge, that is when Chum Kiu gets involved and footwork is necessary.
Of course there are facing and matchig strategies that come into play at CK stage during Bai Jong, and this is where footwork will also come into play during pre-engagement, but in order for me to have any real sense of WC centerline, we must have a point of reference. This is our own position in space, and we can't have that if the first thing we do is start using footwork to engage.