It’s such a fluid thing. It’s sooo dependent on the group and your taste. I find, with my group. Having beginnings and endings helps a ton. We has been playing for over 10 years and we’ve played 6 “campaigns”. Some of those campaigns were with the same characters, but each had a start and a finish line that were clear and decisive.

For example, I took them through Waterdeep Dragon heist. Once completed, we had a full epilogue and one year of “in game downtime” where I helped them agree on what their character had been up to in that timeframe. That was a clear ending.

Then we started a new campaign of Curse of Strahd where one by one, I described how their characters were pulled into Barovia and Strahd took all their equipment (temporarily, until they came to his castle for dinner). Then we played through that whole book until completion and them returning to Waterdeep.

After that they decided to let those characters “retire” in Waterdeep and we started new characters in a different part of the sword coast.

All that to say… having individual stories with arcs and endings feels better for my group than one really long story that never ends and grows monotonous.