Everyone is different, and one size does not fit all; thereby causing complications which require a trained eye to appreciate (read: carry in your head the list of people/procedures to execute in case of problems, and list of things to ignore) in order to accomodate that.

It's called the "practice of medicine" for a reason. You can do everything "right" by the book and still have things go wrong. There is no substitute for eyes on the patient. Ever.