There are an abundance of techniques utilized and taught to target the hips when squatting. Ankle, hip and thoracic mobility, posture, quad dominance, bar weight, bar height, stance and form adjustments are just a few of the things coaches address. To offset spending time teaching appropriate techniques coaches and athletes often select alternative exercises.
In general to target the hips, leg presses are not utilized because the weight gets heavier and heavier as the weight is lowered into the bottom position. This causes the hips to stay engaged during the movement inorder to protect the spine impeding overall development.
Having an exercise with the correct strength curve allows the hips to stretch so they can maximally contract to accelerate the weight upwards. This is why Pendulum created the Hip Press a must in overall lower body growth.
Pendulum Hip Presses at the University of Cincinnati