I don't know too much about neurosurgery (I'm applying into Derm), but I would imagine that there are a group of applicants who cranked out research during M1 and M2 and then got a mediocre step 1 score. Depending on the rest of your application this may warrant a year off. What percentage of students are in this category I'm not sure. It may be worth PMing failedatlife he seems to be pretty knowledgeable about this topic.
I would say that the M1 de-escalation to M2 period is the best time to start and get the bulk of research done. While I can also imagine a group that does this and fails (supposedly failedatlife) most people who I know who adopted this strategy have 250+ steps gunning for Ortho or Derm. Point is I wouldn't see any risk in doing field specific research then because if you don't do tha field because you bomb Step, I could see it valuable in Gen Surg or IM.
I think for competitive fields like Orthopedics and Dermatology from what I've seen, a research year vs. matching sometimes can largely on subjective factors out of your control. Everyone applying usually has the numbers and research due to self selection and most people gunning for these fields are hard workers so it makes sense they'll work hard on whatever rotations/aways these fields require. What I see a lot of which is kind of stupid (but what do I know shooting for IM) is an overimportance of seeking out the right mentors with the right reputation but I guess I'm also detached from the real world after being in school for 18 years. Some people make those connections and get a spot in, other don't or put their eggs in the wrong basket mentor-wise and those otherwise equally qualified applicants slip through the cracks sometimes even with the right mentors for stupid reasons I've heard like they weren't memorable or chill.
To ultimately answer your question OP, I think if you want Derm, Ortho, ENT, or possibly Ophthamology/Urology, you need to know from day 1 how important class-rank, performance, research, and mentorship is to be competitive. At least looking back that's how it would have had to have been for me. I feel like I worked pretty hard in medical school but in order to have been competitive for one of those fields, I would have needed someone to come into my life, hold my hand, and show me how hard I had to work. That's me, some others may be more
talented. I have one or two decent stats but I know I'm not gonna be able to just jump into Ortho (my dream field) as much as I'd have liked to based on numerous factors.
Now that I said that, let's look at the research year. I'm gonna borrow from AK's post and say let's assume that competitive residency = excellent board scores, high Year 3 grades, and high quality research. Say you have 1/3 of those things (strong Step) but your year 3 is mixed with HP/P's and you have no decent research. If you take a year and obtain research, it'll be institution specific and may not even be what most programs are looking for or why they rejected you. The year may significantly bolster your chances of matching at that program, but it won't do loads to your overall resume besides probably give you another shot at the field as well as show your dedication which makes sense if you're already at 2+/3 in those categories. Overall, out of all of this, I wouldn't really count on a research year as a way to catch up. I feel like knowing you want DUEOO from the beginning is actually probably more valuable than shooting for diminishing returns in a research year when you're application is already strong.
Kind of all over the place and I'm not a prospective DUEOO candidate, but I had some second guessing midway through and considered some of these fields and these were my opinions based, of course, on circumstantial evidence I'm surrounded by.
