This is a really simple thing, and that is that it could be interesting to give certain bonuses to one campaign for a few days (for example 3), (for example, more xp, more chances for a card, etc.)
It could “force” players not to play just one campaign, but to rotate them.
In the current phase of the game, when 3. campaign is closed for normal people, this is unnecessary, but after opening it could really change the collective thinking of players.