I'm still pretty new here, but I'm curious just to get a feel for the health of the game... is there any kind of set timeline (implied or direct) for expansions and updates?

For example, it looks like new expansions come roughly every two years. Is that a set in stone timeline for new content... or just coincidence up to this point? Is there an expectation that it'd continue like that, or have they directly said it would or wouldn't? Or are we all just kinda playing it by ear?

Also kinda curious if there's a set timeline for smaller updates.