None of us are immune. Just when you think you can see it all and taste the sunbeam of good finish, a painting problem will like a brick wall whose only purpose is to humble you. So, laugh or be flattened like Wile E. Coyote, to bonelessly slide down the mountain. Or both.
I pick myself off the floor and turn back to face the problem-wall. I wind up to run at it again. And again, and again.
This last ten percent is the hardest.
GOD I love this work.