It's easy to come up with a blasé statement like “I evaluate whether my original project statement will ever be achievable. If I determine that the project cannot meet my goals and objectives, we stop it.” But that assumes you know how to make that determination. Here's some advice on how to calibrate the issues to consider in the “Go/No-Go” decision process, whether the project is something of your own devising (anything from a personal coding project to a novel), or a corporate death march.
For example, "Are you dependent upon resources that are outside your control? If so, can you get them under control?"
And Hugo-award-winning CJ Cherryh points out, it might be that the inspiration isn't there at the moment, but you can set it aside to consider later. She adds, “Never destroy it – for fear it will achieve holy sanctity of ‘might-have-been’ in your memory. Being able to look at it and say, ‘Nope, there was no hope for this one’ is healthy.”
What criteria would you add?"