There's more to writing articles than just writing.
There's also researching and editing to do.
People often make the mistake of doing their researching, writing, and editing all in one go.
They start writing before they've finished researching; they stop to rewrite a clumsy sentences; they change their mind about the direction of the article; the list goes on.
Flitting like a butterfly from writing, researching, and editing is a woefully inefficient use of your time.
Instead, you should focus on one task at a time.
Before you start writing, you should do all your research first.
If you must write at all, create a short outline of the questions you need to address in your article.
This outline will be a guiding compass for your research, which should narrow your focus, keep you grounded, and help prevent you from going off on different tangents.
After you finish your research, you can start writing.
Don't stop to revise your sentences or correct misspellings; it's better to simply let it flow.
Once you're finished, you can edit it as much as you like.
This is when you unleash your inner critic.
Be as ruthless as you like.
Rearrange your paragraphs, rewrite those weak sentences, trim the fat.
You'll be a much more effective editor now that you're not busy worrying about what you'll write next.
By approaching researching, writing, and editing as separate activities, you will become a much more efficient writer.
It may not come easily to you at first, but if you keep practicing, it should become second nature.