Part of the problem apart from handover (which wouldn't typically affect surgeons), is the level of complexity. Much of the idea of the modern surgical training (and many other fields) is that the only way of learning well enough is to do, as much as possible. So we push surgeons to carry out as many surgeries as humanly possible.

Whether we have the balance right in terms of maximizing repetition vs. minimizing mistakes from tiredness is a good question, but it's not a given that reducing the number of hours worked for surgeons would improve patient survival without a great deal of care in how (e.g. ensuring you cut their number of hours without reducing their critical skillset).