Why won't an extension trigger unless Work Item Save Operation is selected?

I created a simple extension with the operationId in the participant's plugin.xml set to com.ibm.team.process.server.saveTeamArea. When I modified a team area and saved it, nothing fired and none of my breakpoints are hit. Then I switched the operationId to com.ibm.team.workitem.operation.workItemSave and switched the extension to a work item save in the process configuration. I save a workitem and my extension is called and my breakpoint is hit. I've only developed Work Item Save participants so far, and I wasn't sure what other differences there are between development for the work item save event and any other event or if there's another reason this extension wouldn't be triggered?