if the action is recent enough then the rule doesn’t apply
Sort of, but not quite right. The rule accounts for this.
The present perfect is used to refer to actions that have been completed in, or have been completed continually up until, the speaker’s frame of reference (i.e, usually, but not necessarily, the present time). For example:
a) John has eaten an entire ham.
b) John ate an entire ham.
In a), John completed the meal only moments ago, within the current frame of reference. While in b), the ham was snarfed down at some indeterminate time in the past. (The just in the original example emphasizes the fact that the action is in the present frame of reference. If you said John just ate an entire ham, the adverbial just modifies the simple preterite so that it becomes the temporal equivalent of the present perfect. English doesn’t just use tense to express temporal relationships, it can use adverbs to do it as well.)
c) John has sheared a sheep or two in his lifetime.
d) John sheared a sheep or two in his lifetime.
In c), John’s sheep shearing has occurred at intervals right up until the present, not that he finished with a ram just moments ago, and it implies that he is a good man to turn to now that your sheep have gotten a bit woolly. In d), there is no indication that John is still in the sheep shearing business, and in fact, he may be as dead as Frederick Douglass.