Somewhat of an unpopular opinion, but as an M4 applying to a competitive specialty going through the process currently, I tend to learn toward quantity > quality. I had 40 abstracts/presentations/publications on ERAS (18 manuscripts either published, accepted or submitted), mediocre grades (Step 1 <240, 3rd quartile, 1 H, etc), mid-tier state school not known for being research powerhouse, and received >20 IIs. The sheer quantity of research has been mentioned on every single one of my interviews.
All of the projects are good quality, although most likely not practice changing. I was not targeting NEJM, Nature, or the top specialty journals (eg, JBJS or AJSM for ortho as an example). Mostly low or mid tier journals.
Residences don't have time to read over any of your research. The typical questions I have been asked:
1) Which project are you most proud of/was your favorite
2) Can you tell me about this project (very generic what you did/results)
3) How were you able to get this many publications (Got fortunate to learn how to conduct my own research/stats early in medical school, got access to large databases where data was freely accessible, built a team of med students to help, etc).
There is a lot they can take away from an applicant who has a ton of research. Namely:
1) This applicant must be highly motivated and takes initiative (eg, grit, perseverance, etc).
2) this person is a finisher and will get things done.
3) This person must get along and work well in a team
4) Student is interested in research, will not need to be handheld to get things done, and will be an asset to our residency
I am not advocating for publishing crap research. As I said, I would not consider any of my research crap. But I do think that being able to learn how to conduct research and pump out a ton of projects does demonstrate many desirable traits that residences (particularly surgical subspecialties) want in a resident. I think you can learn more about a student who has more shear quantity of publications in lower journals than a student who has one middle author in a top journal.