Try writing tourism related articles, where information needs to be garnered from 3-5 sources simultaneously and you will understand the time it requires to write just one.
I kinda disagree with you. For me rewrites are the hardest to write, the reason is most clients think the content is right there in the article and may want to extend a 300 word article to 500 words. Not only is it difficult it's hard to take someone else words and change them. It's just not creative and it is super dull. I type just as fast as you do but with rewrites I type really slowly because I have to keep looking back at the article I'm rewriting. So in my eyes rewrites take more time and more research because not all the information is including in the article at all times. It takes the same amount of time to write an original article compared to a rewrite. Needless to say I don't do rewrites that often anymore.
I would be inclined to agree with a few earlier comments. A team of writers. Its very easy to outsource to a team for like 5 dollars and have 2 people write you 10 articles each in fluent english. The people promoting such offers with quick turn around times stay in business because they take a cut of the profit but they dont actually do any of the work. It's actually a decent business model if you can get yourself some of the writers. Because not only can you easily create content for yourself but then you can provide the service to others whiel you have "downtime" between projects. This way everybody wins!
There are good rewriting tools like bestspinner which will help us save a lot of time. wordflood, power article rewriter are all good manual rewriting tools