Two lines and a circle

How do you know when you are done?
I have been staring at a piece that I have been working on for a while. And somehow tonight I decided it needs two more lines and a circle. I may change my mind after I see it. But somehow I know I am getting close to being finished.

I do not always know. I have a few pieces that have one circle too many and in some cases several circles too many. That goes for lines as well. And I still have trouble knowing when to call it quits. Sometimes I wonder if I am stopping because I am too lazy to add more. Or maybe I am done because I am bored. When I get in a mindset like that it is better to just stop for the night and stare at it in the morning.

So I stopped for the night. But somehow I still think I am two lines and a circle away from the end.