What I would prefer, is somebody who tries to figure it out themselves, even if it takes more time ... just maybe I don't have the answers and would like somebody to give me information for a change rather than just take take take ...
However, if you intervene too late you can make a student go on his way for too looking for an answer that's too complex(for the time frame given to solve the problem) or that's in wrong direction(like trying to optimize a small part of a project that's not all that important) or even more commonly, the student can remain oblivious regarding a shortcut that can make his life a lot easier.
I always think of those problems when dealing with a new intern and I'm still unsure on how to deal with it, but one thing I'm starting to understand is that different people have different personalities(that are constantly changing), so they require different approaches at different moments
As the man says "there is no silver bullet".