Not OP, but I’ll be starting in August. I personally took 2 years, and gap years are VERY common. Over 100 students (~2/3) in the incoming class are over the age of 23 – we also have 2 33 year old students beginning. Most of the people that I met at Revisit took 1-2 gaps years and worked in some sort of community service (Peace Corps, AmeriCorps), academics (Rhodes, Fulbright, etc), or in research (clinical/basic science).
What you do in your gap year is up to you, just make sure you do something productive and is something you can speak passionately about – this is the most important part. Like @MaxPlancker said, most people don’t have publications. I didn’t even after working 2 years in clinical research.