I didn't do a research year personally and I have no regrets yet (talk to me again after match day 🙂 ), but I like the idea of passing on the pearls of wisdom that we've acquired the hard way. Maybe a designated thread to that would be better so that people don't have to sift through the last 8 pages of our anxious obsessions and compulsions to read something useful.
Here's my 2 cents about the research year - they're no guarantee. If you're just doing it to get some more pubs, then that will simply put you on par with the other folks who knew they were doing derm from MS1 or 2 and had long term projects going. There are a lot of derm applicants that were pre-derm almost before they were pre-med. There are also plenty of applicants who switch during MS3 to derm, but they're coming from other competitive specialties (ortho, rads, rad onc, neurosurg, ophtho) and similarly already have more than enough research to show they are "academic" enough. I think the year off can be useful for the MS3 who decides on derm late and has little or no research or derm experience. Even with Step 1, AOA, etc., it's hard to compete without displaying some commitment to the field. Of course there are always exceptions. I think the research year really jumps you into that top tier of applicants only if it 1. results in significant quality/quantity pubs, 2. takes place at a top institution, and 3. if it connects you to the right people. I've heard of applicants who were already strong on paper who took the year off and got their name on 10-15 things at a top program that wasn't their home program, working with major players in derm. That stands out.
Not all 660 of us can say we have that experience and the CV and LORs that come from that. But like I said, there are people out there who accomplish something like that in their 3 years of med school because they decide on derm early, they work hard and they get lucky. Good for them.