It seems to me that if the address position has a spine tilt then upper body weght at address will be on the right foot and lower body weight on the left foot.
In the backswing if a multi-centered hip pivot is used then the weight of the lower body would turn into the left heel and the weight of the upper body would be turned into the right heel.
The pressure is created by the hip rotation, swinging clubhead and the sitting condition that is required to maintain the counter balance to accommodate the swinging clubhead. This is a feeling of staying level.
Imo, weight shift is just a condition of a centered hip pivot that should not move laterally (ideally). Any lateral weight shift will change where the weight pressure moves in the feet.
As we know there are many ways but I prefer less being more as a foundation for efficiency.
Hope that made some sense
