Received this reply to my email request:
Thank you for contacting Lansweeper support.
The 'After Scanning' deployment is indeed intended more for dynamic groups, to make a change based on newly scanned information, whenever it is detected. It's currently not possible to configure an 'After Scanning' schedule to run only once (succesfully). We've marked this ticket as a feature request. Features on the customer wishlist are prioritized based on a combination of customer demand and difficulty to implement. As such we can unfortunately not guarantee this will be implemented or provide you with an expected release date.
Note that you can configure a deployment to retry when it fails. This way, you could launch a one-time deployment, configuring it to try again only on those assets where it fails. This cannot be configured to run after a scan unfortunately.
I can get most of the way to my intentions using this advice.
There is a "Retry during" option that goes out to 1 week. So the deployment will retry for up to a week. This will work for some instances but not for all. If you did this on a large deployment you could easily use up your deployment threads and essentially stop all deployments. Use sparingly.