You can choose what kind of book you want to write. A book that will take you a year or a book that will take you a decade. The main thing is, once you start, don't quit. Finish it. And if it takes you a decade to write the bloody thing, be smarter next time and choose something easier. But don't lie. If you want to create an apogee of verisimilitude, then don't fucking groan over all the research you have to do. Do it. Finish it. Move on.