There is some part of my body that makes me work slower the further I am away from a deadline or the more comfortable I am.
A job that really should have been an hour took two hours for the first section, and then as it was getting late, 20 minutes for the rest. I find I actually work best when it's getting late and I've got some kind of primal urge to do the job quickly and get home. I also find that the quality seems to be best at that time of night. During the day on the other hand, I find that I keep getting distracted and wanting to watch Youtube videos and so on. It means that sometimes when proof-reading, I notice that I had missed a whole paragraph or line.
This is a pretty well known phenomena I guess. I remember that my old manager at a bank I used to work for told me to always book meetings for 430 or later, because everyone will go there and get straight down to business, with no time wasting. It works every time!
I'm sure there's a science to work timing that could be extremely helpful.