Clint Watson has written a piece on his blog:Interruption is the Enemy of Productivity. It takes time to get into “the zone” and you can’t be really productive if you keep getting interrupted.
This is why I only paint at night and why I hate Fridays. I can’t paint when I have small children running round the house and housework chores naggingly waiting to be done. Even if I have made a conscious decision to take an hour out for art, they keep nagging me to get back to work. This cuts down my work time, but I’m not going to get anything done then anyway.
Clint took this from a post by Kris Jordan on a presentation by Jason Fried of 37 signals where he is talking about writing software and running a start-up. Writing software is also an art.
Jason also mentions the fallacy of getting more work done by working longer hours and several other good practices for the software or visual artist. Worth a read and taking to heart.