Within ArcGIS Server Manager, for Dedicated Instance services, there is a statistic for 'Instances in Use:'. This number never seems to read anything other than '0', even when I've confirmed that service is in heavy use. Rather, whether that service is currently being used seems to be reported by 'Instances Running', instead. If I am misinterpreting this statistic, can anybody explain what it actually means? Or is it simply obsolete?
I see the value jump up now and then, but unless there's a long-running operation like a field calculation or version reconciliation, you may not be quick enough to see it. Querying features to render and applying edits are relatively fast operations, though. Refresh the page often enough and I'm sure you'll see something eventually.