I used to have a thousand a day habit (words written not cigarettes) - I sat down at some point and slogged out a thousand words. This was when writing was my hobby, and often it was the last thing I did in the evening. Now I'm writing full time, it's hard to understand why I can't do more than a thousand, some days. I think I've worked it out. I would think all day about what I wanted to write, turn over possibilities in my head while I was busy or working, until I could let it all loose on the keyboard at the end of the day. Now I sit down...to do what? I haven't spent time working on it, thinking about it. It takes me a while to find the threads again, to pick up the story. One advantage of this is I do read the last few days work through, but that's largely with my editor's hat on and I don't change hats quickly.
I still get the blitz days when I write loads because a new scene has consumed me, usually something towards the end that I've been working on for ages in the back of my mind. I'm trying to find a method to set one of those off, so I can polish off the last few chapters. If I find a way, I'll share it, but in the meantime I'm plodding through my thousand or two in the breathless heat of North Devon. There's hardly a breeze even on the beach, it's baking hot.