I completely get what you mean about the Orange Roads and maybe I'm being overly optimistic, but I think I can write a great book without doing all kinds of other "little" writing projects. I don't mean to sound arrogant, but my book idea is really great. I honestly feel like it's just a matter of getting it in the right hands. You even posted it yourself telling us we have to believe in our work and toot our own horns.
Kevin might be right, he may have a book that is accepted on the first submission. There are names for things like that; a hole in one, that's the name for it in golf. Winning a lottery jackpot playing just one dollar. I'm sure you can think of plenty one-in-a-million examples as well.
Kevin, I would say that doing what you love and believe in is paramount to success. Write your best selling book and submit the manuscript. In the meantime, I know you are doing all kinds of "little" writing projects because writers write. Whether it's a blog, a story, a book, or a newsletter for your business, writers write.
I stand behind my posts on this subject as some of the ways to get published. I am learning more every day and loving it. I can't stress enough the importance of proper English and grammar and having someone who knows as much as (or more than) you do to edit your work. I wish you the best and hope you will let me know when you get that "Yes!" and your book is available for me to purchase. Happy writing!