An early example of in-universe continuity and canon in storytelling in a franchise was references to James Bond's tragic marriage. Though two of the first three films after his wife's murder didn't reference the marriage in any way, shape or form the producers began tossing in references to reinforce that the Connery and then the Moore, Dalton and Brosnan 007s were the exact same man with the same life experiences, just on a floating timeline that asked you to ignore the changes in appearance and then painfully obvious drop in age from Moore to Dalton.
So there was in-universe canon and continuity, just adhered to as loosely as possible because the actors kept changing every few years or so and they had to keep the character, well, essentially, ageless after 1985 so he wouldn't end up a seventy-odd-year-old senior citizen by the final Brosnan entry in the series.
But even there, the best you can say about any of those examples is they're just there for flavor. I mean, the Brosnan one was so subtle that most people completely missed it and just chalked it up as a great tête-à-tête between him and Marceau. The number of us for whom it was a piercing (See what I did there?) dagger, was disproportionately small. (Heck, when my friend and I went to see DAD, the place was packed. We were the only two in the whole theater who laughed when he picked up the copy of West Indies. The people in front of us even turned around and glared. Of course, they nay just have been mad because the film had gone to shit by then, but I digress.)
It's been a while, but I don't think Tracy was even mentioned by named in either SWLM or L2K. In both, it's simply stated that he's been married once. For all intents and purposes, both Felix and Mrs. Ringo may as well have been talking about Madeline. Or even that long weekend Bond and Tanner spent in Vegas together.
The only real direct reference was the grave in YEO, but even had the gravestone read "Sadie, Sandwich Queen of Baltimore" (Thus giving greater importance to Not Ernst's last words.), it wouldn't have had much effect on the greater film for anyone besides a very small group who probably spent their evenings wearing out their dot-matrixes in an angry letter-writing campaign.
On the flip side, though, you have Craig's whole tenure that only became a convoluted mess of tangled contrivance by the mid-point of SPECTRE.
I'm fascinated by the idea of a series with no continuity now. Main characters could get killed off and just appear again next episode like nothing happened. One episode the crew works for Starfleet, next they're mercenaries. One week the ship is taking alien ambassadors to a distant galaxy, the next FTL hasn't been invented and they've never encountered aliens. The ship and sets look entirely different every episode.
I don't know if this was supposed to be a joke or a piss-poor attempt at bad faith, but:
Only that of their own creation.
*And even then only that which is germane to the plot.
Yes. If you're watching a murder mystery and the evidence proves Jack was the killer in-part because forensics concludes the killer was left-handed and so is Jack, then, yes, it's important to show Jack south-pawing his way through the movie. However, if it's the fourth movie in a series and even if every single time Jacked picked a pen or a coffee cup in the first three with his right hand, it doesn't fucking matter.