Painting is, more often than not, a series of fixing 'mistakes'. But we don't erase what is there we add to it. the mark isn't put in exactly the right place often but it gives us a place marker to build from.
Each adjustment becomes part of the structure, part of the history of the surface.
What looks intentional in the end is usually the outcome of many small corrections, each one nudging the work closer to where it needs to be.