I know a person who is pursuing Neurosurgery and he does not feel it is not necessary to go through 3 years of MS general surgery before taking up neurosurgery. As a 6-year student, he was supposed to rotate through 10 months of general surgery.
He did not find general surgical skills that he acquired during the rotation, of much use in neurosurgery, other than the very basic knot tying and suturing skills, which can also be acquired through dedicated lab practice.
The other techniques followed in neurosurgery are significantly different from those followed in general surgery. The extensive use of the surgical microscope and bipolar coagulation for hemostasis distinguishes this surgical discipline from general surgery.
Today, neurosurgeons typically use access surgeons (thoracic surgeons or urologists) if they want to perform any unconventional approaches to the spine, which is much safer for the patient.
A lot of post-MS students don’t find much difference in incompetence or spectrum of surgeries and they are comfortable when compared with those having gone through six years of courses.
Globally, there is a trend towards running integrated courses only. Also, in India, pursuing a 6 years’ course after MBBS means you will have one less entrance examination to worry about.