It depends on the research project. If it is a PhD project, it usually takes 3 to 5 years to complete. Even before the completion of the project you can publish papers. In some countries, students are to publish at least two papers before the submission of the thesis. If a research project is of shorter duration, you can publish the manuscript maybe within a year. Suppose you want to conduct a bibliometric study with the research papers published by Namibian scientists in a particular time period, Using a proper database you can get the necessary data for analysis, and you can finish the project in just two to three months, and publish the manuscript in less than a year. Best wishes.
Unless we talk about "journals" where the authors pay to get anything published, a good quality paper for a reputable journal cannot be written very fast, neither will it be refereed fast - both processes take time. I would advice to use quality of research as the main criterion and not the time necessary to write the paper. From my experience, it takes time to write good papers, but this is very often rewarded by their faster publication.
Most of the time it is dependent on the quantum of work involved. Average a very good research concept should not take more than a month to be developed. A manuscript for publication should also take a minimum of about 12 weeks to complete.