SharePoint 2013 WorkFlows Association and Content Types

Hi,

I'm studying for an exam the ability to associate a workflow to a content type in SharePoint 2013.

Probably i'm confusing:

YES:  http://technet.microsoft.com/it-it/library/cc262735.aspx (See PLAN Workflows)
NO:http://msdn.microsoft.com/en-us/library/jj163181 (Unlike....) 

Can You Help me to understand?

Well, then what is the sense of the method

http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.workflow.spworkflowassociation.createwebcontenttypeassociation.aspx

Tnx