I have been in a Men's Bible Study for over 40 years. We have almost always studied the Bible itself rather than a subject or idea. We have most often used Barclay or Wiersbe which are excellent materials. Recently, I convinced the group to try the New International Version Application Commentary. I think this might have been written as a reference book but we have found it to be perfect for our studies. Our group meets one morning each week for two hours. We start with a cold cereal breakfast with fellowship, followed by study for almost an hour and then prayer. Daniel took us 18 months and we are halfway through Isaiah after 30 months. This is not a quick read or a shallow study. After studying a book I don't expect to feel the need to repeat the same book for 10 years. My adult Sunday School class studies John for 6 weeks from some author almost every year but I never feel we do it justice. This series is often useful as a typical commentary reference book when looking for a clear understanding of a passage or story from Scripture. I recommend the NIVAP.