I'm not saying it did not fit the contexts where it was used.
I just really tend to notice repeating patterns.
I do as well, and sometimes they can be intrusive. (Most annoying to me is a character who repeats the same phrase over and over throughout a book. Okay, okay, we get it; this guy is annoying and unimaginative. Enough, already!)
In the case of "unspoken truth," the choice was deliberate. For one thing, the term has fascinated me since I first heard it in "The Enterprise Incident," as the Commander's response to Spock's "It is not a lie to keep the truth to oneself."
I'd never really thought of it quite that way before. It had RL implications, as well as mitigating GR's rather rigid dictum that "Vulcans can't lie."
We saw what happened later with Data blurting out whatever came into his head. Vulcans could not have survived interaction with each other, much less become master diplomats like Sarek, interacting with a variety of aliens, if they always told the complete and absolute truth. There are things known as "tact" and "common sense" that color our truths every day.
Saavik, as a young cadet in TWOK
, doesn't yet know this. That's why she's so upset with Spock's "lie." His explanation, "I exaggerated," gives her something to think about, and look at from a different perspective.
The Saavik I was writing about was not that far removed from those events, and the situation I placed her in required her to examine each of her interactions for possible pitfalls.
It's not that Vulcans *can't* lie (any more than "Vulcans have no emotions"), but that they choose not to, except when telling the truth would do more damage.