Where's the trouble in dispatching a message for all devices connected to a given Apple ID, those devices checking whether the timer is in the past (and silentl

Where's the trouble in dispatching a message for all devices connected to a given Apple ID, those devices checking whether the timer is in the past (and silently discarding it in that case), and setting a local timer to the desired target time? As a sibling commenter said, this isn't about millisecond precision, but making sure the timer telling me to take the cake out of the oven I set on the tablet in the kitchen will ring on my phone.