OK I just had a similar situation and checked veeam forums for an existing thread and here we are
The one thing is that surebackup stops when one vm fails and the other thing is that there is probably a way to boost up this thing a little bit...
I had to use a application timeout of 1800 seconds for my two DC's to make sure that the job won't fail. I am pretty sure that most of the time you could run the tests much earlier but you have to keep the timeout that high for those 3 times a month where the services won't be that fast up as normally (e.g. when the latest windows updates have been installed). I would say why not try to execute the scripts every 2 minutes? It won't need much ressources and if it fails, wait for the next 2 minutes until the timeout occurs. If it is successful after say 10 minutes, surebackup could start the next vm and would be faster in the end.
Probably you have even thought about this behaviour, maybe there are good reasons to not do it this way (allthough I can't see any at the moment)??