Even though we would know many legal answers immediately based on prior cases or ongoing legal research for cases or seminars, there are still times where legal research is needed. For instance, laws change, new case law develops, some issues have unique elements. Even a law firm with decades of multi-family housing experience must sometimes do legal research.
Any good law firm can conduct legal research and draft legal memoranda in any area of the law. But the time and efficiency of that research can be significantly affected by the extent to which the researcher already has a good conceptual framework of the area or issue, and maybe even a published case citation or two from internal files to begin with. This general knowledge would typically cause the legal research and drafting time to be significantly more efficient, which then reduces the legal fees paid by the client.