My main objection to these types of books is how overly verbose they tend to be. With a few exceptions, this category of book is built around a nucleus of few possibly valuable pearls of
wisdom, and then 300 pages of filler is added. Usually lots of anecdotes ("Let me tell you about my friend Alice..."), checklists, and needless exposition.
If this really is wisdom, it does not follow that it takes 300 pages to communicate. But I suppose the propounders have to make a living somehow.
To be honest, I don't object to buying the book if it's really got some good wisdom, but I would be more likely to if they shipped with some sort of executive summary.