Detecting a Beakon region when iOS is in deep Sleep Mode

We are looking to reliably detect entering/exiting a beakon region even when the iOS device has been asleep for some time. There are many comments on the internet suggesting that iOS region monitoring can take a long time to react when the device is in deep sleep. Is this true? Is there anything we need to do to guarantee the beakon entry state is detected straight away even if the iOS device has been in the pocket untouched for 2 hours?

Afraid this is entirely up to iOS. Modern iPhones use hardware-accelerated passive scanning that most of the time should result in instantaneous enters and exits, even in deep sleep, but we’ve also heard that’s not 100% a case—pretty close though, from our knowledge.

What app are you trying to build and why does it require instant enters?