Team is always evaluating the result from the signature campaign. In my opinion if a signature campaign that has been running by a popular site will be going ever longer due to the numerous factors

The revenue from the platform will become main consideration to continue the campaign or not. Remember that only those big sites which have been getting millions dollars of revenue from the gamblers unlike the new sites which have been starting from the bottom.
This is also affecting the duration from the signature campaing that being launched before.

I think that any gambling platform providers have various reasons why the campaign was only going in a short time.