That being said I've known many people who look with a contrarian opinion on this. In college I was there for The Cleveland Orchestra's handoff from Christoph Dohnanyi to its current conductor Franz Welser-Most. I remember reading an article from him at the time about how he refused to study anything but the score. He wanted to get the performance thoughts from the composers music, not someone else's interpretation. There's a certain level of artisanship there that I guess I can understand that point of view.
That being said, we're talking about HS or JH students here... I say do anything you can to help them become great musicians!