I'm of the opinion that while it's a necessary part of learning to repeat exercises to advance your skillset, school is much too focused on this element of learning, and in doing so to an unnecessarily rote extent (I suspect because it's the easiest way to try to get it done).

The problem is that this mishandling gives people a bad taste for associated activities, especially STEM subjects, and it's rare for people to subject themselves to what seems like an incredibly boring process when they're not being forced to. As such, most of the competency they may have been forced to gain is lost, along with potential passion.

Even repeating exercises can be fun when you understand the motivation behind it. For example, if you have a real passion for understanding Newtonian physics, the parts of calculus that might be 'rote' when unmotivated and part of a purely rote process can become some of the most enjoyable.