What is a good publication rate?

I really think this is the wrong question.
I increasingly get irritated by grant reviewers passing judgement on people, particularly junior scientists, because their "publication rate" is "not high enough" or "good but not outstanding".

First, we should be concerned with the quality of the publications; i.e. the significance, originality, technical difficulty, and reliability of the scientific content. Quality is more important than quantity. A major problem with science today is not that people are not publishing enough papers! Rather a problem is the low quality of what is produced. If you look at Einstein, Feynman, Onsager, .... their publication rates were not very high. Furthermore, even lesser mortals such as Mermin, Hohenberg, Haldane, ... have publication rates, particularly early in their career, that might be rated as "good but not outstanding" by some grant assessors today.

Second, given most papers are multi-author one should be concerned with the quality and quantity of the individuals contribution to each paper. Just dividing number of papers / number of authors is not good enough.

Third, one needs to factor in opportunity. The publication rate of a junior faculty member with little funding and a heavy teaching load should not be compared to a well funded senior faculty member who does no teaching.

Do I look at publication rates of grant applicants and job candidates? Somewhat, but only as a secondary measure, and in context. I do like to see a somewhat "steady" output of a "few" papers per year in "decent" journals. I do sometimes get concerned about people who seem to produce "little" relative to opportunity. But, what I am really concerned about is whether the person is producing some useful and interesting scientific knowledge.

Finally, given all this silliness let me encourage you to try and keep your publication rate up by using publons and choosing to work with organised people who are good at getting papers "out the door", but with integrity.