3rd year on through residency and beyond really blurs the line between 'school' and 'work'. If you mean sitting down at home with a textbook and reading, drawing diagrams, making notes, etc. like the first two years the answer might be something like 1-2 hours/day depending on the rotation and the proximity to the shelf exam. But your real learning comes from work, rounding, cramming Surg Recall prior between cases, conferences, lectures, and the various times throughout the day that you can find time to crack a book or surf Uptodate about one of your patients' conditions.