Shadowing is very important for jobs where the outcome of failure is potentially harmful or costly. Biological research is done almost exclusively through an apprenticeship-like training system, and part of that system is that you shadow a mentor when you start. (You’ll also continue to work closely with your mentor so that they can continue to supervise you personally for a long while before you’re allowed to work on your own)

My understanding is that hospital or medical work is pretty similar in that regard