Many crypto-gambling sites have different marketing strategies. Some of them prefer to run signature campaigns for a long time, while others prefer for a short time. In the case of Betfury, we can notice that they prefer to run campaigns only during events, and as far as I know, the current campaign will last at least 4 weeks. Of course, there is a chance that Betfury may decide to prolong its campaign, but I wouldn't expect it because the birthday event will end soon.
There are a lot of companies that run short campaigns but they do it once, and there are some companies like Betfury who run short campaigns but they periodically remind themselves and apparently it brings them the best results if they stick to this strategy. The campaign will continue this and next week, and nothing is clear about its further fate.
It is not really a bad one. If you keep having it, after a while it may or may not become boring and known and not get too much attention anymore. But if you do have it, then stop, then restart again then you keep reminding people that you exist and that will give people a lot of time.
I am not saying that it’s the best, I am saying there must be something for everyone, and each casino has a different style. I am guessing this worked out well enough for them so far that they decided to keep it going. I am sure many who tried the same thing may have failed, and many who tried the longer version both succeeded and failed as well, it all depends on how well you do it.