My first year, I was pretty careful. I was feeling my way in a new and different situation, and being extremely careful not to make mistakes. Oh, I took a chance or two---the lie to McGonagall after the Troll Incident, for example---but I was trying hard to be cautious. Getting in on the Hunt for the Stone, although it was something I hadn't planned on, proved to be invaluable experience, as well as cementing my "good girl on the right side" image in Dumbledore's eyes. Of course, if I had managed to obtain the Stone, that would have been very useful---once I was sure that it was the Philosopher's Stone, and not some sort of cleverly-constructed booby-trap designed to sucker the Dark Lord in, of course. I can hardly believe that somebody as clever as Dumbledore pretends he is couldn't have thought of that course of action; create a false Philosopher's Stone and send the real one out of the country. Hiding it in that idiotic Mirror was rather clever, I admit, but Harry got it out of there with no problem---and if I'd been there, once the Squirrel was dealt with one way or another, I'd have had that bloody Stone so fast...