I wasn't interested in the premise of Double Helix, and even though I noticed there was a cover with Calhoun on the cover, I assumed it would be a minor role and that I'd be lost without having read the other books. I was moderately confused when it was referenced briefly in the next NF book, and then very confused when it turned out to be a key element a few books later, so I only figured out what had happened and doubled back to read it during the long gap between "Being Human" and "Gods Above."
The thing about those crossover miniseries in the '90s or early '00s is that they were very loose crossovers, designed so that each individual book could stand alone and you didn't have to read them all. They weren't telling a single story like
Destiny or
Coda would do, just several standalone stories dealing with a common premise or a common catalyzing crisis. Think of the various Maquis episodes that were done across TNG and DS9 in the season before
Voyager premiered -- "Journey's End," "The Maquis," "Pre-emptive Strike," "Tribunal." Each a standalone story, but with a common theme and continuity. It was kind of like that. Sometimes it was even looser, just a common theme like four books about Section 31 or the Klingon Day of Honor.
So if a book was part of a serialized series like
New Frontier or the DS9 post-finale books, it would be much more closely tied to its own series's continuity than to the other books under the crossover title. It wasn't until
Destiny that we got a crossover that was all one continuous story.
And there is some value in reading books from the period immediately preceding Richard Arnold's "Reign of Terror" in publication order, because there was a "proto-novelverse" going on, with a number of characters and situations shared among multiple authors. As I recall, there was a Vietnamese junior officer (named Nguyen, of course) showing up in multiple novels at the time. If not for Richard Arnold, it might have developed as fully as the more recent Novelverse.
You're thinking of J.M. Dillard's novels, which had their own ongoing continuity within themselves and featured multiple original, recurring security-officer characters, including Lisa Nguyen. In the early years, there was often continuity between successive books by the same author, but there was only infrequent crossover between different authors' continuities. Dillard's characters stand out because she did so many books in fairly quick succession and featured them prominently across the sequence. The first real crossover between different authors was Margaret Wander Bonanno's
Dwellers in the Crucible, which picked up on Duane's Romulans and John M. Ford's Klingons. Dillard's security chief character of Ingrit Tomson got picked up by Duane and one or two others, but I don't think any of Dillard's other characters did. The biggest single piece of connective tissue in the '80s "proto-novelverse" is A.C. Crispin's
Time for Yesterday, which references at least a half-dozen other novelists' works (Duane, Ford, Brad Ferguson, Jean Lorrah, Vonda McIntyre, and Howard Weinstein), most of which were otherwise unconnected to each other.