That’s an interesting topic you chose to write about.
I am one of the people who write one story a day here and coincidentally, I wrote about originality a few days ago: Originality Does Not Exist, We Should Aim For This Instead.
You are correct in saying that original content is very hard to produce when written at such a pace.
In the story above, I stipulate that quality, “original” content can be created based on authenticity, which is something I aim for in all my stories. Even though the message is the same “junk” as you call it, at least I always try to bring my own perspective to it.
And I’m speaking for myself here, but I do not aim to make a career writing.
In fact, I only wanted to write one story a day so I could improve my writing skills. I didn’t aim to get published. I didn’t aim to be known or be successful.
My point is, I agree that if the goal of writing every day is for fame and fortune, it’s wasted effort. Chances are the content will be “junk”.
But when the stories come from authenticity with no other intentions then just spreading good ideas through life experiences, I personally believe that, even though very hard, quality content can be produced at such a pace.
It’s a rare thing, but a few writers have successfully done that here.