Thanks! Sorry/surprised to see the Metrics feature is enabled only for applications with more than one running dyno. My biggest question remains "When should

Thanks! Sorry/surprised to see the Metrics feature is enabled only for applications with more than one running dyno. My biggest question remains "When should I enable a 2nd dyno for my app?" Even better, I'd like to say to Heroku "when this app is overwhelmed, enabled at most X dyno(s), and turn them off as activity decreases".