Currently, the execution script in NZB #2 options is executed after each individual par2 set within a download set is completed. In my opinion, and others I've spoken with, there should be an option to only execute once all par2 sets have finished within the download set.
Also, if there are no PAR2's for a download set or if PAR2 checking within alt.binz is disabled, the execution script should still execute, or at least have an option to.
Lastly, an option to execute the script minimized or hidden would be excellent!