It's funny you put it that way; that's much the way I viewed it going in, and what I wanted and hope for. I read it know it as a focal point for many of the novels that I assembled for reading. It had an additional, somewhat erroneous significance, having to do with the coming of TNG. I tried to pin down which book was the "final" novel of this sequence, the last TOS novel released before Star Trek started to broaden. Somehow I incorrectly landed on Time for Yesterday as the marker for right before TNG's arrival. I figured it would help to be aware of that transitional moment. I had a view of finishing the book as the beginning of the end for the idea of a "Star Trek 80's novel continuity" as a concept. My list still has something like 9 novels past that point that I thought of as kind of a death blow to the idea...nine additional books is a pretty respectable "victory lap" if it can be called that. (To say nothing of the books that I've skipped/saved for rainy days, such as Chain of Attack, Uhura's Song, and the ones I read decades before my current readthrough). And I read Memory Prime thinking of it as partly of a new era. It didn't let me down, felt loaded with references to the previous books on the list...and one sneaky little reference/nod to the Tkon from TNG's "The Last Outpost". I had mixed feelings about that moment. To circle back to the idea of Time for Yesterday as a finale, I read it in that way. It's impressive how it manages to be epic in scope, as well as very focused on individual characters on a relatable level. As a finale, I think the major missing element was not having Ingrit Tomson as the security chief. Imagine her leading the other returning security characters from Vonda McIntyre's novels, with her habitual gall, she would have been the perfect character to beam down and interrupt Spock from being naughty! I was struck by Time for Yesterday as kind of it's own story, though, I ended up feeling like maybe I wouldn't have needed to read all the previous books as a lead in...if I were in the right frame of mind. I think I might be kidding myself though, the little continuity nods might have driven me crazy, wondering what I was missing! I was glad to be in the know, with just a little regret that I hadn't tackled Uhura's Song and Tears of the Singers before going in.
Kirk's early log entry in "Where No Man Has Gone Before" refers to it as being more than 200 years since the Valiant launched. But IIRC, the Okudas explained in their intro to the Chronology that when a character said something happened 200 years before, they decided to make it exactly 200 years for simplicity's sake, as it wouldn't really make much difference to the overall picture if a particular event was 199, 201, or even 206 years before. And the Okudas were obviously open to the Chronology's dates being adjusted, since First Contact later changed the date of Zephram Cochrane's first warp flight from 2061 to 2063 and VOY changed the end of Kirk's 5YM from 2269 to 2270. The book was always meant as a general guideline that subsequent canon could contradict if need be. The character was named Diane Morwood, taking the first name from Diane Duane and the last name from her husband Peter Morwood. (I believe that Debt of Honor writer Chris Claremont is friends with them both.) https://memory-beta.fandom.com/wiki/Diane_Morwood
Yes, Chris is friends with both Diane and Peter (as am I), and Chris had a character named Diane Duane, but Richard Arnold made him change it because he didn't want a character named after a novelist. So Chris stealth-named the character after Diane in a way that only people who knew her would get.
God, practically everything from that era of Trek fiction can be explained by writers trying to do an end run around Richard Arnold and his arbitrary rules.
Deprecation doesn't require prior acceptance. Case in point, years ago (especially around the early days of the Java Programming Language), web browser suppliers frequently added their own proprietary extensions to HTML, without ever bothering to go through the RFC process normally used for Internet open standards. Some of them did so for malicious reasons (Microsoft's "embrace-extend-extinguish" strategy for supplanting open standards with their own), others simply because they were in a hurry to fill a genuine need. A few of those extensions eventually did go through the RFC process, and did get accepted as standards; most of them got superseded by standards; some got formally deprecated without ever having been accepted.
Clever. I've named a few characters in similarly sneaky ways. No shit! (And this comment would be funnier if we had the appropriate emoji!)