How good a record is good enough? In truth, I don't think we even know enough to get the order of magnitude right. The best I can offer is that you need to record as much as you are willing to.

But this estimate is essential. By deciding to pursue this course of action, you in effect state that you estimate sufficient probability of it being enough to justify the additional effort. You can't say "I don't know" and act on this knowledge at the same time.