I found Covey pretty insightful but you know the old saying...different strokes.
I actually have found Covey insightful as well.
Over the last couple of years, I have started to cull my library. (full disclosure most ministers are addicted to books and, relatively speaking my library is no where near what many of my colleagues have) That said, I started by assuming that I would start at the top left shelf, take down a book, review it, decide whether to keep it. After three years it was clear that that wasn't going to happen.
So, new and more effective method. I take all the books on one topic - leadership/ preaching/ stewardship - whatever, and put them all on the desk. I then establish which of the two or at the most three voices I am interested in listening to and the rest go whether or not I like them - or have even read the actual books. This has been much much more fruitful.
One of the challenges I have in my work (consulting and leadership training among other things) is that people just keep going to another and another book and not actually working on the issue. So, recently, I have started including the admonition to stop reading more and more and more as it just makes people crazy. In fact, my instruction is increasingly to get a hobby or an outside interest rather than obsessing.
I have been reading/using/interacting with leadership material since I was ordained in the 80's and hardly any of it has stood the test of time. A few - Covey/ Collins/ Various ancient Chinese generals but, others, not so much, and, as mentioned the willingness of others to accept leadership advice (or any other advice) uncritically is astonishing.
And don't even get me started on "Star" leaders who are later disgraced. :grin: