Ignoring the business side of it, let's take Halo for example, should Halo have stopped making games after Halo Reach?
I think it might have been better to do this because it would have left Halo in a ‘good stance’ for it's last game, feeling for the most part completed. Instead we got 2 more story lines on top of that that people aren't happy with compared to the original trilogy. I loved Halo 4,5, and Infinite, but I think I would have much better memories of Halo if they stopped after Reach.
I find that many popular game series want to go on forever, when it would have been better to stop after a few games and a finished story. Maybe there are ways around or ways to prolong the point when a series should stop. Let's again take Halo, what if we followed different people/teams for the stories in Halo 4-5 and Halo Infinite? I think that has the possibility to turn out better and prolong the point of when it should stop, although the constant risk of having to make entirely new stories with new people should be acknowledged.
I wonder if this is why Valve limits themselves to 2 games in a series, or follows the suggestion from the paragraph above.
