I was introduced to this concept recently on BookBrowse and explored how it applies to my lifetime of reading. Two attached documents explain what I learned and how it might apply to you. BookBrowse Doors Analysis.docx - Google Docs]
The analysis I performed can be seen in the following spreadsheet.
[Book Doors for Book Browse.xlsx - Google Sheets?
This spreadsheet can be a bit intimidating but, at least for my 74 books that I chose from BookBrowse contain 35 books which are quality books by the Four Doors approach. I will continue to perform this analysis on more of the books I intend to read, and will especially head toward four Door books.