As a consultant, I am routinely given hundreds of new files from new clients which are usually a mix of Word documents and PDFs of policies, procedures, and standards. Then, throughout the course of the engagement, I often have to pick out certain phrases or topics from these large datasets in order to reference them in a report.

Windows File Explorer can do this to some degree. I am not sure if File Explorer looks at the actual content of the documents or just titles. Either way, Recoll is magnitudes better and is absolutely worth it for my case.