Rules for 'Alert Cleared' messages

Does this control make more sense at a per-user level, or a per-chain level?  i.e. do I as user Steve want to say for all alerts, regardless of how I received them, I only ever want to get the Acks or Clears via at most SMS (even if I got them via voice call). Or for all alerts, regardless of how I received them, I only ever want to get the Acks or Clears via email (even if I got them via sms or voice call).  This would affect that user, for all chains, but be controllable by that user.  Or does it make more sense to have this control be at the chain level?So whoever creates the alert escalation controls which mechanisms are used for Acks/Clears? This would be specific to a chain (so a less critical set of alerts may have the acks sent via email, while a more critical set will have acks sent via SMS, too). But users would not be able to individually control this themselves (unless they had rights to change the chain.) If it was changed, it would affect all users that are destinations of that chain.