Sometimes I find myself having spent an entire day without writing a thing. Yet I don't really feel that it was time wasted. I have to work out these little kinks in certain scenes in my mind that niggle at me.
And if they don't have anything to do with the current scene I'm writing?
I just feel like those problems can cause problems all over the story. There have been plenty of times where I've found solutions somewhere else and that's led me to change what I'm about to write in a seemingly unrelated scene or sequence.
All the scenes further the same plot. The thing is to not get carried away or let 'thinking' be an excuse for not putting my pen to paper or my hands to the keyboard. Writing is a way to solve those issues and untie those kinks, too, along with actually getting the story completed. It's just that on some occasions I have to visualize the problem first.