Setting measurable daily goals is an effective practice for attaining success in any endeavour. Many writers set themselves a specific word or page count to write each day and this helps them maintain momentum.
But that approach doesn't work for everyone.
While I've long been a fan of setting goals, in writing my novels I've never done well with a target daily word or page count. I only find that helpful when I'm actually laying down a first draft. But that's only a few months out of the total creation time for a book.
The rest of the time I'm either plotting, outlining, revising or editing. And as necessary as these stages are, I don't produce a lot of new pages or words each day, so targets in these areas are totally pointless.
Setting a goal and consistently failing to meet it is, for me, more discouraging than not setting a goal at all. I much prefer to set myself a certain number of hours of writing each day.
This is another of the many things I've carried over from music. In the years I attended music college I practiced a minimum of 4 hours a day, usually longer. But that daily minimum was written in blood. If for some reason I couldn't do it I felt extremely anxious and unsettled.
Not every practice day felt productive. Some days I'd see a small improvement in my playing, on others I'd struggle to match what I'd done the day before.
It didn't matter. So long as I put in my hours I knew I'd eventually reach my goal. And I was right. For despite those days my practice seemed totally ineffective, a time always came when my playing made a sudden significant leap to a higher level.
So this is the method I use in my writing - I simply put in my hours each day, in whatever form it happens to be. A goal I can consistently attain no matter what phase my project is at.