Length and size of their signature campaign are two important factors for their signature campaign success and also marketing effects.
Sorry, but what do you mean by signature size? I'm interested to know what it means because you said it’s important for the success of their campaign.
If I am right, there are gambling sites which only run contests, prediction giveaways for many months before they expanded marketing in this forum to signature campaigns. Oppositely, there are companies that start with signature campaigns, nothing more until many months later with marketing expansion to contests and more.
What you just said is right but I've been here for more than 7 years and I can tell you that the most successful casinos/companies around here, are those who started their journey by launching a signature campaign.
Without a signature campaign, contests and giveaways are useless, imo.