This study analyzed the factors required for a researcher to become a professor in the humanities and sociology, science and engineering, medicine and biology, and general studies fields. The study focuses on research productivity and analyzes the impact of hiatuses in research production on promotion in universities as well as the time at which such hiatuses have the least impact on promotions. I divided the factors required for promotion into three categories: academic performance (the number of published articles, books, and competitive grants and funding sources acquired), social elements (gender), and elements related to the duration of periods with no research output and their timing. The results show that the probability of promotion to professorship increases as the number of papers in Scopus, the number of books published, and the amount of acquired competitive funds increase. As expected, longer declines in research productivity reduce the probability of promotion. However, it is not always necessary for researchers to publish continuously throughout their careers; the results show that a decline in research productivity other than during the first five years and the period from 20 to 30 years after the start of the research career has no influence on academic promotions.