Having just spoke with my advisor, and speaking on occasion with other professors, I have come to the impression that one should not "subpublish." Let me say what I mean. I'm a 3rd year graduate student right now, and the professors I talk to seem to say that it is not a good idea to publish many small papers along the way to a result: that is, holding fixed the total mathematical content across N papers, it is best if N is minimized. I was trying to understand why. My advisor cited the reason of "reputation" and I have invented my own reason that perhaps there is an upfront cost to the process of writing and submitting a paper so that although effort per length may be constant, it is to my advantage to pay the upfront cost as few times as possible. (Finding a referee is the only upfront cost that comes to mind, but keep in mind I've never done this before.)
Can someone expand upon how reputation is relevant here i.e. for fixed mathematical content why it looks bad to come out with many small papers? Are there also benefits to the community or the knowledge pool that I'm trying to expand however slightly by writing such papers if it all comes at once in one big paper? One would think that if I "subpublish" that actually since my results become available more immediately that it would benefit the community if I did so. The only person it would seem to possibly hurt is me if I were to get scooped.
Are there other ways in which upfront costs to the whole process of publishing may happen?
I am interested in all my questions in both advantages and disadvantages to me, and also to those who would use my work.