The research depends on the novel or collection, etc. All of my books take research. There is always something I do not know or need to find out about. Research is vital. For the story collections, it may take six months.
Novel research can take quite a long time.
Research for M.C. Higgins, The Great covered details about strip mining, steel making and the open hearth method. Unions, mountains, country living, steel poles, hunting, swinging vines, skinning rabbits, underwater tunnels, and so on. So you see, research can be quite extensive. I do like all of my books and some better than others. In The Beginning .