Grad student just getting started here, this question popped in my head this morning when stumbling across a former colleague that has already published a lot but in journals with low h-indexes.
Generally, is it better to publish more articles in journals that are cited less often/have a smaller reputation, or publish less in higher impact journals?
Bonus question : does the answer changes if considering early-career scientists vs later stages?
Actually, high impact journals get that way from the quality of the papers in them, not the other way around. So, I'd suggest that you look at it a bit differently.
Write as much as you can based on your research. Make the papers as high quality as you are able, with new and interesting results.
Publish them in the "best" journals that will accept them, but "best" means the most appropriate for the subject matter as much as anything.
If you get rejected somewhere, revise and send the paper out again, perhaps to a less prestigious journal.
Over time you will have a "mixed" portfolio. But you will have a good portfolio if you keep at it.
Keep a lot of irons in the fire. You will probably spend the bulk of your effort at one project at a time, but keep notes on other ideas that arise along the way and outline new potential publications as you have the time. If you get stuck on your main project, pick up one of the others.
No, the answer doesn't change. In fact it is the way to get, successfully, to the later stage.
Started as a comment but got too long:
To be practical, I would aim your first papers at "decent" subspecialty journals. Not Science/Nature (covering all of science). Not journals covering all of a field (e.g. Journal of American Chemical Society, Physical Review, JAMA). But the next level down (e.g. Inorganic Chemistry). They are not hard to get into if you (A) do classic, good, science and (B) write it up clearly and honestly. [Of course if you discover phlogiston, do a press release and send it to Science.]
In general, the mags from ACS or APS are "decent". But you will also learn equivalent from Elsevier, Wiley, etc in your specialty. However, the commercial publishers tend to saturate the waterfront, so avoid their lowest impact journals, new launchings, etc. unless you have no other option.
Usually you can't save up work and then have a better package that (thus) makes it into a higher ranked journal. Note: sometimes you might be able to self review a campaign of work. But even in that case, you would be better off having published earlier in the more specialized journals.
