Suddenly occurred to me that there is one more situation in which Exacting Strike is better: when you are reasonably certain that a regular strike will kill your first enemy. This might vary table to table, but Jason Bulmahn certainly seems to describe when enemies are on their last legs. And it also counts when you are facing enemies that you sort of know have hp barely higher than your strength modifier.
One good that came out of 4E was the notion of being blooded at half hp.
In our 5E campaigns (and now PF2) we try to restrict descriptions (of health) to being blooded or not being blooded (as opposed to details such as "I have 14 hp left, so I need a bit of healing, but not your biggest heal").
(And of course the outliers as well "I am in perfect health" and "I am down and dying")