That's not true. I've tried every setting (opt-out, manual, automatic) on every device and Apple essentially does it the same way regardless: repeated notificat

That's not true. I've tried every setting (opt-out, manual, automatic) on every device and Apple essentially does it the same way regardless: repeated notifications to manually update. Opt-out works the same as manual. The only difference between manual & auto is that auto will pre-download OS installers, but you still have to manually run the update.