In Google Tag Manager, every single Tag requires a Trigger to fire. Every single Trigger requires an Event condition to activate. Sometimes, these Event conditions are obfuscated under template semantics, but you can also create a Custom Event Trigger, where you specify the value of the ‘event’ key in dataLayer that fires your tag. You can read more about the relationship between GTM events and Tags in these two posts:
With Google Tag Manager, there are a million different ways to make your tagging setup leaner and more flexible. The reason this should be a priority is because the UI isn't perfect. The more tags you have, the more difficult it becomes to manage your assets. In this #GTMtips post, I show you one of my favorite ways to put your container on a diet. Tip 13: How to create a Generic Event Tag I've seen a lot of containers that suffer from the same problem.