If I ever have to make the decision that "good enough" actually is, then that tells me it isn't. I guess I am too used to working to drawings with tolerances that are actually criteria for selling the part. If it's out of print, it's most likely scrap and will not be accepted by the customer. The company reputation is riding on furnishing parts that are in tolerance, and if it isn't, is surely isn't "good enough". My inner quest used to drive one of my bosses nuts. If I made a "finish" cut, and was not as close to nominal as I wanted, I'd cut it again. It took many years to realize that there are valid reasons to either leave well enough alone, or to deliberately restrict yourself to maximum material condition instead of going for nominal every time, no matter what.
For my own projects, I do whatever suits my mood. Sometimes I just try to see how close to perfect I can make it, others I consider function and give myself more tolerance. But, I always have a tolerance zone to work in. And I stay in it.