When a script task executes is it running Asynchronously or Synchronously?

When a script task executes is it running Asynchronously or Synchronously?
I am asking because I recently encountered an issue with a query rule which was set as the output of a script task. It was not delievering results back to the process. Since I knew there were values which should return I moved the rule to the output of the attended task. This worked results are returned. So hence my question, I was have always assumed all nodes run synchronously unless you are handling a call for sub proc.
Not really sure why the script task would complete without delivering output unless script tasks only have a set amount of time to deliver. This behaviour was witnessed in a 6.5.3 build so I suspect it may not apply to newer 7 builds....

OriginalPostID-105215

OriginalPostID-105215