Just out of pure curiosity -- were these all with the same group of players? Were the run in succession or concurrently?Just looking at the 5e HBs
HOTDQ. Completed twice
SKT. Completed
COS. Completed
GOS. Completed, and half completed.
DH. Completed but rushed as I really didn't like it
BG:A. Dumped as I really, really didn't like it.
ROTFM. About 8 pages from the end
Sometimes we plan a campaign -- open ended or with an expresarc or time limit -- but it doesn't go off. The group breaks up, or interest wanes, or their is an unsatisfying TPK, or any number of other things that can kill it before its natural and satisfying conclusion. It isn't a question of "did you have fun" -- you can have an unsuccessful campaign where everyone had fun, and even a successful one that people kind of hate-played.100%??
I mean we all decide at some point that we are at a good stopping point. I've had groups that had to disband because of external factors I suppose but that is very rare. So my campaigns in the old days ran years. Even now, they'd run a year at least or longer. Maybe I don't understand the question.
I guess I never plan an ending for any of my campaigns. So there is that. I would say my group just tends to decide that it's time to end one and prepare at some point to start another. I'm as likely, more likely actually, to be the one thinking it's time for another campaign. I will add though that a new campaign might just be a new group in the same campaign setting (probably a different sandbox). Sometimes I fast forward time a bit and sometimes I don't. So the old PCs become NPCs in the new campaign.Sometimes we plan a campaign -- open ended or with an expresarc or time limit -- but it doesn't go off. The group breaks up, or interest wanes, or their is an unsatisfying TPK, or any number of other things that can kill it before its natural and satisfying conclusion. It isn't a question of "did you have fun" -- you can have an unsuccessful campaign where everyone had fun, and even a successful one that people kind of hate-played.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.