In my experience, campaigns often span a relative short amount of time, and i'd like to change this.
On one side, this is because downtime is often hard to play and justify and make meaningful: you're an adventurer, why would you wait in a town for days when there's adventure to be had? Travel around and find the new adventure if none is at hand!
Long voyages (when they happen) seem to be the only exception for time passing, (though often these are turned into interesting, sequences of brief events) it is hard to justify an adventure having to span months, or even years. Also, often these long voyages (3week +) change setting, which makes it hard for past actions to influence the future, which is what i'd like to achieve by having campaign that span longer in time.
What are plausible ways to add "span" to a campaign, so that it is plausible for the party to want to wait some months in a place (or in a set of places)?
These plausible ways would be sped-up at the table, the goal would be to have the world move on for months, while the table has not.