The service has support for individual cool downs for users and effects. The UI just isn’t accessible by users at this time, we’re working on a way to make it not overwhelm the streamer with options when it comes to setting them up.
As for start/stop button to only trigger effects during the game during certain periods. There are a few ways we can accomplish this feature request, but we’d have to think of a way to ensure it’s easy for the streamer to enable/disable and doesn’t increase the amount of support requests we get from viewers asking why their effect doesn’t trigger.