It is no different than any other hard measurement. What is the best heart rate for you, as an example? In many, it is more a directional check. 100% is like

It is no different than any other hard measurement. What is the best heart rate for you, as an example? In many, it is more a directional check. 100% is likely not to give you 100% confidence. But, 0% will make everyone less confident. And if you have two teams, one at 50% and one at 80%, it is probably safe to assume that the testing culture is better for the 80% team. And why branch coverage, as opposed to path coverage? Largely because you hit the easy to measure things before you worry about the hard to measure ones.