" of course you're affected when the government decides on a new policy ... but how does knowing about it on the same day or in the same hour mitigate that?"
It saves people a nasty surprise when the policies they relied upon fall out from under them, or to try and head off future issues by calling up their representatives. For example, I was able to call up my representative regarding changes in immigration policy. Because other people aren't paying attention and don't call their representatives, I actually have an outsized voice and influence on the matter!