It seems HomeAssistant will not call the same script multiple times at once; why is this?
For example to wrap push notifications into a script for simplicity if the script is running any other calls of that script will fail; with a log entry the script was already running. This causes these other notifications to be skipped.
But what we’re doing in that script could run multiple instances at once as it’s typically just firing off a message to an upstream web service to deliver the notification by whatever means.