The sentence might have 25 words, the page, 300. An article is 6,000-8,000 words. The book is 80-100 thousand. If you wrote a sentence a day, you could finish a book every 11 years. That's pretty respectable, considering scholarly careers of 35 years where someone might have written 2-3 books. Writing a page a day gets you enough material for a book every year, which nobody ought to be writing.
When I look too closely at the word count, I produce wordier writing. I'm hoping the days I write 300 words, that those are 300 better words, than the days I write 700. On the other hand I live to force out a few extra hundred words at the end of my writing session.