All MySpool devices are subject to notification throttling. This is done for two reasons: one is to prevent flooding communications with unnecessary messages. And the second one is to save us some money: we have to pay for every text message!
Each device is allotted 300 text messages per month. In case of repeating alerts within a certain interval, that interval will be increased. When the issue has been resolved, the alert interval will be reset back to the original 5 minutes.
Here are the details on how the text interval is managed: