I've gotten into this a little on this thread and on another thread about flaring the feet in the set-up. Important to not only flare the feet (turn them out) but also have the knees turned out as well. I'll re-post that info here about how the body works and how it makes sense to turn the feet out, especially the rear foot, rather than perpendicular to the stance line.
The hip is a ball and socket joint. The thigh bone (femur) ends with a rounded projection or ball (femoral head), which fits into the socket (acetabulum) of the pelvic girdle.
The hips go from flexion to extension. Flexion of the hip occurs when the angle between the torso and thigh is decreased. When this angle is increased extension occurs. Ok so what does all that mean? We play golf on an inclined plane and to get the hips to accomodate for that, the trail knee has to lose, release flexion. Check out Rory and Sam Snead, their trail hips are higher than the left at the top of their back swings, it will be the opposite on the followthrough. Flaring the feet our helps the trail knee lose flexion.
The toothpicks and clay was an example Dana Dahlquist gave me (below) If we try to turn the hips level, staying in address flexion, that's when we're working against how our bodies we designed to move.