Many years ao there was cult movie called El Topo. It was by a
Spanish Director/Actor/Writer whose name I wont try to spell.
One of the characters in the movie spent all of his time building
complex geometric forms out of small sticks. At one point the man
realizes that "Too much perfection is a curse."
I continue to remember that line. In art and in life one needs to
stive for excellence and never be afraid to revise and correct but be
aware of the point when it is time to move on.
In my own art when I reach that point with one piece I tell myself
that the next piece will be better. With my students I try to push
them to do better but when I sense that they can't go any further I
stop pushing and encourage them to move on.