Signature campaigns mostly help with exposure and maybe bring in new customers, it has nothing with building trust. What the service delivers is what builds trust. There can be several reasons as to why certain service stop signature campaigns, as already mentioned by some members.

But to be honest, according to my observation, casinos or services that run long term campaigns are the ones to seem to thrive more rather than those to keep starting up short campaigns. Once you introduce lets say a 2 months campaign, you get known in those two months after which signatures are removed and next thing that happens is people forget that the service even exists