In my situation, our desktop build group has their own subnet. When a new machine is added to our domain, I have a startup script that installs the agent. They then check into ePO in their own group where I have this option enabled.
I then have an automated task to delete these computers from ePO every night and once they're deployed for use, they check into ePO again with non-build IP and get created in their proper groups based on tags/sorting. At this point, I no longer have the "run task at every.." enabled.
I don't generally have a lot of older machines that get powered on but when they do, the deployment task with "run immediately" generally works. If it doesn't it will stand out in reports and/or the dashboard.