Ideally, the larger the promotional budget and the more participants promoting the brand, the more likely it is to generate interest. Some brands only run campaigns for a few weeks due to limited budgets, but I believe this is crucial for brand awareness. The more participants and the longer it lasts the better for the casino, the casino will naturally become more famous.
Yes, the more people are exposed to a brand, the more curiosity it will generate. This will certainly lead them to visit the website, in this case the casino, to learn more and, depending on the budget, even try it out. The length of time spent on the forum is a way to build trust with users; it's unlikely you'll want to deposit money on a newly created website. I also believe that general campaigns like, signatures, social media, and articles, contribute to increasing brand visibility.
It all depends on the company's objectives and the budget available. Aside from some websites that promote it, I only see casino ads on TV, during soccer matches (that's how it is in my country), and advertising on TV is much more expensive.
It is the same over here as well most especially on cable TV, casinos are only advertised during ongoing sports match, and like you said, this mode of advertisement is one that not only cost alot of money, but also will need the participating casinos to be well connected in terms of knowing people with great influence.
And speaking of advertising here on this forum, I would also very much agree that the consistency is key to success of any casino running ad campaign here, marketing is everything when it comes to running a casino business, it's easier to create a casino than it is to find users/gamblers who will be playing on the casino, this is why marketing is very important and without it, it would be better that the casino wasn't created or built at all.
So, running a long term ad campaign is a necessity, one that is not negotiable for a casino that is very serious about succeeding, most gamblers will like to see a casino ad consistently everyday for more the two three months before ever deciding to maybe try the casino.