The "precise" part is not even necessary. In short, if 90% of the time guessing the intent works, then I may want to use that system anyway. The projects almost every one of us work with are underspecified anyway, but we have a decent intuition of what should happen (or we just don't care in many edge cases and let the default failure happen). We can read the result and say "is the good enough?" and iterate as you described.