IBM RTC Rest API + pre-conditions and follow-up action

For all I know both participants/follow up actions and advisors/pre-conditions can fail the save, so the code that runs runs within the save transaction. The operation ends after all the code of the behavior is run.  

I use delay operation In pre-conditions and follow-up action for "speed" test of create/update Work Item by Rest API. Rest-client (I use curl) wait ending work of all plugins (pre-conditions and follow-up action) on operation Save Work Item.