Too large of a progression angle
Remember geometry? The bigger the progression angle (angle of your foot when it hits the ground), the less distance covered and consequently the more steps per mile. This can be due to genetics or muscle imbalance and is usually a blend of the two. There is no ideal way to fix this issue at the foot because the problem is usually not local, but often a gluteal weakness—especially in the gluteus medius—leads to poor pelvis control.
Fix it: Loop a therapy band around your ankles and do side-step shuffles. Improving gluteus medius strength can help reduce the need to turn out the feet for added stability.