Some kids use more than one device, maybe they have a phone and a tablet that they use.
At the moment if there is more than on device attached to a child’s profile then the limit won’t be stretched over both the devices. If you give a limit of 1 hour for the child they will get 1 hour on one device and another 1 hour on the other device, so 2 hours in total.
In the future we’d like to change this so that the limit it shared between the devices, if that’s something you’d like to see please vote for that feature by pressing the Send Us Your Ideas button on this page.
In the meantime a workaround that some parents use is to set up a child profile for each device. So there’s one device per profile that way you can set a separate limit for each device, and you can set each device to have 30 mins, if you want a total of 1 hour Daily Limit on both devices.