Where before I was taking an hour or two a day and doing as much as I could, I now have the whole day to do 2000 words. I try to get the 2000 before noon.
The focus is different. When I only had a few hours and was doing the writing during my lunch and breaks, it was broken up and disjointed. I spent almost as much time deciding what to write as actually writing. Also, I was focusing on the writing and very seldom paid attention to the editing. I was treating it as a hobby.
When I made my rules, I decided that I have to spend half my time writing and half my time editing, so I’m doing much better there.
Also, my stamina appears to be increasing. Where before I struggled to get 500 words per day (2000 during NaNoWriMo) I can now do 1500 words without struggling and sometimes get as much as 3000 or 4000 words if I push. Part of that is time, but not all of it.