There are two kinds of writing days...

The days in which you have a word count requirement, and you write one or more scenes or pieces of scenes and advance the word count along. YAY for these days!
There are also days in which you have a word count requirement, but you realize there's some foundational issue that needs to be restructured, deleted or moved about. You work on that for a while, and then you realize you've used up your writing time and the word count is actually LESS than it had been before. Sure, the book's better, but they can be a bit dispiriting.
Ah, writing. Such a cruel mistress.