Earlier this evening I used the REST API to create an AWS group containing an account device for the purposes of billing monitoring. I didn't specify any services to monitor; I only provided a billing bucket and report path prefix. (Side note: the example under (2) at https://www.logicmonitor.com/support/rest-api-developers-guide/device-groups/aws-device-groups/ is out of date.) Nearly four hours later, LogicMonitor has discovered a handful of instances for each of the Cost By Service, Cost By Operation, and Cost By Region data sources. It has yet to discover an instance for the Cost By Account data source. (Those four comprise what comes with billing monitoring.)
The billing bucket had report files waiting to be retrieved as soon as the account device was created. I have the active discovery schedule for each of the aforementioned data sources set to 15 minutes, though that shouldn't matter because, as stated previously, I force active discovery upon device creation. I have the polling frequency for one of the four data sources set to 1 minute for testing purposes, with the rest set to 1 hour, but that shouldn't matter either, because surely instances are polled at least once when they are discovered, regardless of the frequency setting (?).