Zwei usually runs the campaign at random times based on what I have observed. They don't really need to run a campaign currently though it will definitely help for exposure sake as you mentioned.
Zwei is in charge as the manager to run the campaign for Wolf.bet many times. Each time Wolf.bet run a campaign, it is a long one, one to two months.
I think wolf.bet doesn't need to run their signature campaign again as their traffic site is enough / popular than before. But yea i noticed it too they would running it again on the future just like Haunebu said above.
Anyway, lets focus disscuss about wolfbet instead other gambling site on here.
Gambling sites have different style to run their signature campaign on this forum. They can run continuously for months to years or they only run their campaigns when their sites have some big promotions, a wave of many new games are integrated on their platforms, special events in a year.
They have to consider when run a signature campaign can bring as best effects as possible. Traffic as you said is one of things and sometimes gambing sites will need more than traffic.