To be fair, the movie itself played it really fast & loose with how the Nexus worked. Kirk relived specific moments of his life, while Picard had an entire fantasy existence with a family he never had and where (IIRC) his nephew Rene was suddenly his son. It was impossible to exit, until suddenly Kirk & Picard were able to do so at will.Again, that's not how the Nexus works. As I said, it let him relive his best memories, so his own mind chose what points in his life he experienced. (The novelization showed him experiencing alternate, happier versions of his times with Edith, Carol, etc.)
Basically, the Nexus did whatever the writers wanted it to in any given scene.
Dennis O'Neil. Just one L.For instance, when Dennis O'Neill and Len Wein wrote episodes of Batman: The Animated Series adapting their '70s comics stories, they set them in the B:TAS continuity instead of the DC Comics continuity.

They also incorporated the villain Lock-Up and BTAS' version of Mr. Freeze's backstory.But that's not sharing a continuity, just one continuity borrowing a concept from another, like Batman comics incorporating Harley Quinn and Renee Montoya from The Animated Series even though the comics and the show were in distinct realities.
I'd say that most modern comic book movies only try to stay broadly consistent with the comics, if for no other reason than to still surprise the people who are familiar with the original source material. For instance, the MCU version of the Scarlet Witch has slightly different powers than her comics counterpart, and was hugely affected by the death of her brother Quicksilver, who, the last time I looked, is a still-living Avenger of many years standing in the comics. Not to mention the whole variance of the mutant backstory, necessitated by the X-Men being licensed to a separate studio. But the big important things, like her being a misguided villain who becomes a hero and her romance with the Vision, are more or less the same. Or in another example, the Sam Raimi/Tobey Maguire version of Spider-Man didn't start fighting crime until after he graduated high school. He also never dated Betty Brant, even though she was his first girlfriend in the comics. And he didn't meet Gwen Stacy until long after he was dating Mary Jane Watson.Which makes it puzzling that there's so much effort by modern comic-book movies to stay consistent with their source comics and not offend the comics fans, given that the readership numbers of comics today are much smaller than they were before the direct market took over, and it's rare for a single comic issue to sell more than 10,000 copies. I figure it might be because comics fans are very active online and that makes them disproportionately influential in creating positive or negative buzz. Fans of prose tie-ins to a TV/movie franchise are not going to be anywhere near as prominent online.
For me, it's much more important that they try get retain the essence of the characters than the exact trivia of the characters.