When you deploy many automation agents (remote systems) each with several metrics it is more efficient to manage non standard metrics using a template.
A template allow you to create the metric configuration, then deploy it to many systems at once and propagate changes to all systems in one action.
Let's assume you monitor the temperature on 50 remote systems using a metric. You can create the Temperature metric as a template and roll it out to all 50 systems in one action. If you now need to make changes to the metric you only have to update the template and then propagate the changes to all 50 remote systems with one action from the template.