To be financially successful as an online writer, you have to be a writing machine. That is, assuming you've already learned about page ranking, anchored backlinks and SEO keywords. And you are putting that knowledge to work.
Your goal is to earn money from the articles you write. Think of each article as a separate deposit into an investment account. Obviously, the more deposits you make, the more interest income you will earn. That is a very simplistic view of the quantity of work you publish.
What about the quality? If each article is a deposit, then each deposit would be for a specific value. If you are publishing poorly written content, or content of little or no interest to anyone except yourself, the market value of your work is very low. You may as well be writing in a personal journal. On the other hand, if you are producing high interest, well written work, the monetary value is higher. That value will increase as you produce more quality content because your readers will begin to trust you, and read more of your work.
Quantity plus quality is the winning combination, and should be what you are striving for as a writer.