I can't help with the art part, but as general behaviour, I have also noticed that if I am busy, I get more things done than when I have an entire day free.
I read somewhere, or someone told me at some point (not sure), that if you are in an office and you want to get something done, find the busiest person in that room and give it to them.
The idea is that a busy person is already in the zone and getting stuff completed. Someone who isn't in that zone that day might be lazy and slow (does not mean they always are but at this point in time they are not working hard) and will therefore not kick into high gear to get stuff done. They will most likely drag their feet.
I feel I do the same thing. If I am already in the zone, doing stuff, then knocking a few more tasks off is easy, but if I started the day slow, it's hard to then kick into high gear and get stuff completed.
Personally, a strict routine has helped me stay a bit more on track with stuff I want to do, as that routine eases me into getting stuff done. The only issue now is to be consistent with that routine at the start of my day 