quality: a graph showing when to stop working towards perfection

Knowing when to stop investing more effort into a project can be hard to do.
In the quest for quality, there is a point where additional effort will no longer contribute significantly to the quality.

Absolute perfection is never achievable. Reasonable or acceptable quality is.

The trick is to identify the zone of acceptable quality that is appropriate for a given project, and stop working when the quality reaches that zone.