So, here's a question I have as a naive undergrad.
Does someone choose a project thinking, "This project is high caliber. If I get it done, it's going in Nature" or do Nature papers just happen from regular work that gets lucky?
I ask this because it seems there are big shot labs out there that regularly publish in Nature while there are big shot labs that don't. I work in a big shot lab, my PI is editor of a very major journal, chair of dept, etc. but almost no papers end up in high impact factor journals. All the work is just ho-hum observational stuff that gets churned out to mid-level journals.
So, are Nature-worthy projects chosen and specifically sought after or do they just happen?
While we all like to think that "top" journals like Nature, Science, Nature Genetics, Cell, and NEJM are there for anyone who makes a great discovery and solid work... in reality these journals are generally for famous PIs who have a habit of repeatedly publishing in them.
You will often find "top" labs with "famous" PIs who only publish on these top journals. Once you become one of them, you can certainly publish there with significantly less than something that is "breakthough". I'm not saying these journals are closed to everyone else- far from it. But it becomes a habit. These journals will typically require a LOT a secondary experiments done at the whim of the reviewers, and reject papers at the slightest hint of displeasure from a reviewer. Of course, if you are a famous/respected PI, you are more likely to have a reviewer assume you know what you are doing, unless the reviewer is a bitter rival or is working on the same project or some other polical reason to screw your work. Furthermore, if you believe you've got something, and the editor rejects it, a big shot PI can just call the editor and bully them into publishing it. I've seen this more than a few times.
Cell IMHO is somewhat of an exception. I have spoken with the editors and they are much less likely to REJECT manuscripts, and more likely to suggest additional excperiments. Submitting to Cell more than likely means you will publish there, but it may take a year or more after your initial submission.
As someone who has gone though a PhD with many manuscritpts, I can tell you in hindsight that there is a lot of politics in publishing. Sometimes it's disgusting. I can also tell you that you never know what paper is truly considered "breakthough" until years after it is published, and IMHO these papers are unlikely to be published in these exclusive journals. They certainly will be referenced a lot though. Also, Nature and Science are well regarded, but are so non-specific in content that they are really not as good as several other journals.
Furthermore, I will also say that as a grad student I think it is folly to set your sights to these journals. If it means an extra year of work for a Nature paper instead of JBC... seriously, publish in JBC and go on to your career.
I do think you should have a minimum standard for Impact Factor, and that should be dictated by your field. In genetics, for example, I would try to publish only in journals with IFs above 7. In other fields this may be impossible. That ensures that people will read your work and you will be cited. Now that I'm Pathology, the top journal in the field has an IF of apprx. 6.