There is a psychological stigma associated with quitting, yet most people quit many different undertakings over the course of their lives, from childhood hobbies to New Year resolutions to business projects. Seth Godin, actually wrote a book on the subject, called “The Dip.” He argues that quitting can be a valuable tactic, but it should be done not at the point when most people do it (e.g. the 23-rd mile of a marathon). It is best to either quit early in the project, when it is “cheap,” or to stick to it until the end. The definition of “the end” can vary, but imposing (early in the project) a limit on maximum amount of resources that would be spent can help alleviate anxiety towards the end.
I think that a similar approach can be adopted to photo projects. I wrote earlier about the importance of declaring a post-processing stage completed at some point instead of tweaking the image ad infinitum. Perhaps, additional insight can be obtained by analyzing when most photographers quit their processing projects. Once the typical quitting points in the workflow have been established, it would be best to either quit earlier or push beyond them.