What does ‘justness’ mean in the following (literary) examples?

Examples from the internet:

• "A conceit is a comparison whose ingenuity is more striking than its justness..." (Helen Gardner on Metaphysical poetry)
• "In poetry, they must be allowed to excel all other mortals; wherein the justness of their similes, and the minuteness as well as exactness of their descriptions, are indeed inimitable."
• "The purity of his style, the delicacy of his turns, and the justness of his characters..."

I think the following definition of the word makes sense in the context of literature: conformity with some esthetic standard of correctness or propriety. But I don't fully understand the definition or how it applies to comparisons, similes, and fictional characters.

The OED has

Justness

3. The quality or state of being right, proper, or correct; conformity to truth or to a required or agreed standard; correctness in amount, proportion, aesthetic quality, etc. Also: exactness, precision, accuracy. Now somewhat rare.

1832 Compar. Coincidence Reason & Script. I. viii. 311 The following considerations appear to us powerfully supportive of the justness of the foregoing answer to our fourth and last question.

1876 M. Arnold Lit. & Dogma (ed. 5) Pref. p. xxiv After we have got all the facts of our special study, justness of perception to deal with the facts is still required.

2006 W. I. Miller Eye for Eye ii. 23 One can never underestimate the basic moral and aesthetic justness of getting perfectly even.

Thus justness of comparisons similes, and fictional characters, indicates that the comparisons, similes, and fictional characters are finely crafted so as to be objectively apt and accurate in the context and serve a complementary role in the literature as a whole.