Better for who, the school or the applicants? You could argue that it's better for a school to interview a larger number, since it would therefore theoretically get to learn more about a greater number of applicants, and then be in a better position to choose the ones they really want. Of course, it takes a lot more time, energy, and resources to interview a larger number of applicants as well.
You might also argue that interviewing a larger number is better for some APPLICANTS as well, for it gives those who interview very well a better shot at an acceptance (as opposed to perhaps not receiving an interview at all, and then never getting to "prove" themselves).
Then again, maybe interviewing a smaller number is better for applicants, for it increases an individual's chances of being accepted if an interview is granted (looking at it from a purely statistical standpoint).
I don't know how to vote...I don't think there's a clear answer.