I've done it multiple times now since I've graduated from college. It makes you uneasy each time and shortly afterwards I definitely questioned myself. But today, I don't regret it one bit.
I think that's probably telling in itself. I've GTFO'd twice; one time was by my own choice, while in the other I had to be helped along by the organization a few months after I failed to follow my sensible instinct to resign. Both times, once I was finally out the door at last, I found myself feeling like a weight had come off my shoulders.
I could be wrong, but I don't see any way it's possible for that feeling to come along with a lurking realization that I'd made a mistake. (Certainly it never has in my experience, at least, and I've made plenty of mistakes.)
