There's a clear difference between new casinos that launch a branding campaign solely to promote their brand, which is therefore short-lived and limited in impact(introduce it to the community), and established casinos that have more than just brand awareness behind their signature campaigns.
Long-term marketing campaigns require huge budgets, but their most important return is that the brand remains alive in the minds of users, making them remember it whenever they think about gambling and betting. These campaigns don't just rely on providing the necessary budget and a professional marketing team; more importantly, the service's reputation is paramount, as this is the primary factor in marketing.
With about two years of appearance in this forum, Rainbet is no longer a brandnew casino at least with their time of appearance here. I can not remember since when Rainbet run their signature campaign, and perhaps other contests but their signature campaign in my memory already has lasted several months. That is not too long, but long enough to show that they see signature campaign is a good marketing type for their business in Bitcointalk.
They truly have marketing budget that has been used for both signature campaign and contests for months, but is their budget too big and is their business capital is too deep, honestly I don't know.
As all companies, their marketing programs are only solid if creating enough exposure, effects and bring income back to the company so that their marketing budget is like a live and sustainable cycle.