I think even moving as fast as the average student is a generous assessment. My dad was a math teacher at a public high school in Southern California. At the end of his career he was the math dept chair. He retired recently but he was constantly battling administration who wanted them to focus on bringing up the bottom of the class. It was a battle that partially led to his retirement. The admins just wanted the test scores to go up and they saw focusing on the bottom as the easiest way.
What do they do in the current system? Get stuck in a class that can’t move faster than the average student?