From an author's POV in a shared universe, my goal is always to tell good stories while facilitating the easy telling of MORE good stories. I've often referred to shared universes as parks or gardens. This actually draws a little on my lumber-magazine days (yes, I did that too). I don't remember much about lumber, but I did learn about silviculture -- the planting of forests for optimal growth and fewer fires. If you had two trees planted too close together, fighting for resources, you get problems. (This is half the trees in my backyard.)

One of the things that develops in shared universes is that you get many stories/trees drawing on the same roots; that makes for challenges. They exist in every franchise that's been going on for awhile. Even FRASIER had to address why his parents were described as dead in CHEERS. Just to take EU examples: the Sith were a species AND a movement. So were the Mandalorians. There were interesting stories behind that, but it meant taking paragraphs or comics pages out to explain all these things when it was relevant. Added to the challenge. It was kept remarkably coherent; lots of smart folks working very hard. But it meant spending as much time looking backward as forward.

I'm a professional: I can make sixteen overlapping and/or conflicting stories work. I've written for lumber magazines: I can do anything. But proper shared-universe cultivation can either make the difficulty factor go down or up. I try hard to tell stories that make it easier. First thing @Randy_Stradley ever told me about writing Star Wars: "When you define, you confine." Words for living in any shared universe.

It's one of the key concepts in my shared universe seminars: never say "never," always avoid "always." Every definition closes off avenues. They could've ignored it; Sam Malone's first wife was introduced for a one-line joke in CHEERS and vanished forever. But it's better when you're watching out for future story avenues as you go along. Saves from entanglements, imperial and otherwise. LOST TRIBE was the hardest continuity challenge I ever faced: Related stories simultaneously in development set both before, during & after. The FATE OF THE JEDI books in production were set afterward; CROSSCURRENT was partly simultaneous; KOTOR comics before, during, and after!